Yes this is called gain. It is partially why this method does not produce as stable temps.

One reason why RHPs are such a bag of nails probe placement. If you are uneasy with a UTH probe a RHP which gets hotter should be a greater concern. In my test enclosure maxed out mine delivers a 138ºF hot spot and a 88º ambient. The new style UTH deliver 97ºF hot spot with 77º ambient. I would suggest a fail safe is required with a UTH as they have such a high max temp. (Unless it is in an arboreal set up where there is always a low temp retreat.)