Did someone attempt to hijack me? Or Steam bug? Need experienced advice.

Hello all, this is my first time posting on these forums, and I had something happen today that I need advice on.

I got an add earlier from someone who saw a TF2 Outpost post of mine wanting to buy an unusual I had for sale. After greath length I decided I was willing to do the trade. We both hit accept, but an error comes up for both of us on the trade. Shortly thereafter Steam servers went down for me. This was approximately around 6:30 Central time, or slightly before. I verified that Steam was actually down using this website: http://www.downforeveryoneorjustme.com/ , and it told me yes, steamcommunity.com was down.

I did not notice when this happened, but when I next looked back at steam, I was getting the message "Your account credentials have expired, please log back in." I have seen this message before on other accounts, usually when an account is inactive for a very long period of time, Steam will ask you to verify you are the real owner of the account still. However, my Steam account is rarely offline and I am always active with it, so it seemed very odd that Steamguard was prompting me with this right now. Steam community was still offline at this point. I was continously trying to log in an another instance of Steam with an alt, to see when Steam came back.

Eventually I was able to log in on my other instance of steam with an alt account and consulted a friend about all this. I then tried again to log into my main account, still getting the random steamguard message.

Here was my concern at this point: I had heard of Swag [Inc] being hacked and Steamguard was bypassed completely. I figured anything might be possbile, which is why I became suspicious after being kicked off. When I looked at the emails Steamguard sent me, the request to be unlocked from Steamguard was indeed from my current location and IP address. I was only hesitant based on suspicion at this point. I did not know if by some method I could be unknowingly authorizing someone elses computer, perhaps someone attempting to hijack me, if that was indeed the case, by authorizing myself here and now. What I ended up doing was changing my Steam and Email passwords, and then I went through with authorizing this computer with Steamguard.

My biggest source of concern is that the person I was about to trade with when the trade error happened, then steam went down, is on trade ban probation from valve. I do not know why or when he was put on trade probation, and there is no other marks against him on steamrep or any info on the trade ban. I would not want to post his account unless someone knowledgable had extreme suspicion after reading this post, as he could simply be innocent and it could be some kind of bug related with Steam and I could be acting paranoid, but I really have no idea at this point. Regardless, I do not want to sound like I am accusing this person not even knowing what just happened.

I cannot trade for 5 days, and naturally if this person was innocent in all this, I would still like to sell my unusual to him after that is over. But I do not know if what happened to me was some kind of hijack/scam attempt or not. I have never heard of anything like this happening in a scam, but I really wanted a second or even a third opinion on this, as I don't know if its anything that has come up in the past as far as anyone knows. Is it possible to phish someone simply through a steam trade? I don't know. You all will have to forgive me, as I have pretty much thrown logic away for the moment to err on the side of caution to avoid possibly losing my account.

Alternatively, if anyone has had similar experiences where steamguard kicked them off when Steam was offline, that would be helpful as well. Thanks, and I really hope you guys can help me with this. If there are any other details anyone thinks I should post, let me know.

TL;DR
-I was in trade with someone on trade ban probation
-trade error
-steam goes down
-steamguard kicks me off steam while steam community is down
-did someone try to hijack me?

That sounds like a simple coincidence. I don't think it's possible to hijack someone through a Steam trade.

Someone most likely did not hijack you but just in case I recommend changing your Steam password.

Thank you for the quick response. Another thing to note is that I did not click any links or enter my information anywhere, nor did he post any kind of link at any point.