The toilet is of the new style that has no flange going down the drain. It is flush. That worries me, but I finally called in a plumber - he grumbled about it but admitted they usually work.
The idea about a crack or busted washer at the tank is a good one. I checked though, and no weeping at the bolts or drips from where the tank meets the bowl. I'm about at the point of just getting a new toilet - the cocntractor's crew could have banged it around a bit. Was fine for 2 years though. Maybe I need to lose weight or stop dancing on the tank...
The flange is PVC, but since this was a rehab by developer 4 years ago, who knows> I have noticed that the wall behind the toilet is settling - 1/4" below baseboard molding in ajoining room. Still, the floor is a flat surface. Could the settling cause the flange to twank out of level?
Yes it can.
You'll fare better by starting a thread and posting pictures on the Terry Love Plumbing Forum. Pictures will really help.