For what it's worth, John, Tony Colegrave, a guy whose opinion I very much respect, says to apply Proofide to the top surface only, as I remember. That said, I have applied Proofide to the under side of my 3 Pros, but only once, usually. I normally apply only to the top when it needs a touch up. Which isn't often. Colegrave's contention, again, as I remember, is that applying Proofide to the bottom of the saddle doesn't allow the leather to breathe, or something.

As for the OP's dilemma, just a guess here but I sort of suspect that the heat and friction from that miracle synthetic somehow drew the Proofide up to the surface. Or that a bit too much was applied and didn't sink in well. The stuff is mostly wax, after all, and will melt and become tacky again, with warmth. I too use a hair dryer of heat g*u*n on low to help the stuff soak in a bit, then wipe off the excess. And I use as little as possible.