I doubt it.

Probably just a lot of upvotes in a short period of time.

It's a pretty cool idea.

As far as I remember every time I post a comment it always shows at the top for about a minute saying "0 minute ago", but in this case it was the second comment right after I posted. Anyone else noticed this?

This is not always the case. New comments get upweighted, but they do not get "pinned", if that makes any sense.