Problem was small leak at toilet base after every flush. I figured wax seal was leaking, and after removing bowl, I was right. What I noticed was that the metal (and plastic) flange that holds the bowl mounting bolts was only pressed into the drain pipe.
To make the bowl more solidly mounted, should I:
A: Bolt the flange into the concrete.
B: Use the other 2 mounting holes in the bowl with some washers, nuts, and red heads coming up from the concrete (a bad option should I change the toilet later to one with only two mounting holes).
C: Put a bead of silcone around the base of the bowl (also not a great option since it wont show leaks easily).
BTW, I replaced the wax seal with one of those Fluid Master wax-free bowl gasket kits. This is the second one I have installed and they work awesome.