Yes, it does take a little while for it to get into sync. This isn't a five minute process. What type of enclosure (glass, tub, etc)? Where is the heat tape (taped to the bottom of the enclosure, running along the back of the enclosure in a rack)? Where is the t-stat probe (sandwiched between heat tape and bottom of tub-if taped, taped directly on top of a back-run of the heat tape)? If you're using papertowels there should be less of a difference. I was using 1/2" Cypress and I did have to crank mine up a bit to get a decent hot spot. I never really fret about a single degree up or down...better than running the UTH at 130 wide open!

Normally shouldn't have to work that hard though. I would maybe get another in then send that one in for warranty replacement and you'll have a spare if one craps out. I would highly recommend getting a proportional t-stat eventually vs the on/off action of the hydrofarm.