Hasn't it been there for a while? I've had it at least 2 weeks or longer and I'm sure I got it from the Market.
I just remembered because I used chrome to phone to send it's updates to my droid lolThat must be correct because I don't see it in my downloads in the Market.
I just think I would have remembered installing an .apk file. I don't remember doing that.
Getting old .it's a pain.