If you want to keep a BP, it sounds that your temps are correct. RHPs, at least in my experience, are great at creating a nice even temp gradient, after a little fiddling to dial it in just right.

It sounds like you don't have a temp gun, handy thing. You probably want to have one, it will measure surface temps where as your typical thermometers will just measure ambient air temps. My suspicion is that if you measure the surface temp of the substrate under the RHP, you'll find it is 91 or so.

Typically, if the ambient temps are good, then the surface temps take care of themselves.