Just keep in mind that sometimes last online times break if your internet or steam's connection gets hit, for example, if you see everyone has the same last online time.
And seeing as how the entirety of steam went down for like the past half day, this isn't an impossible explanation for that happening. (and it only coming back online around 3-4 hours ago, chances are that isn't really Stevy coming online, but just steam borking.)
not to be a debbie downer but that's probably just how it is.