I'm not very familiar with Version 2, but it may be going potty. Have you scolded it ever for going potty on the regular floor? If so, it may be partially potty trained and be going to the bathroom. Were there little squiggly lines all around it? If so it was using the loo.
it was taking a bath. it's one of those random things your pet does when you leave it alone for a while. mine does it all the time. sometimes it even rools around on the bottom of the screen if it's board.... kinda weird, isn't it?