I have a 850 grams mojave male who has been an aggressive eater but the past two times I have tried to feed him he ducks his head under his body..not balling up but jerking his head under the middle section. Temp is 90 basking spot and 80 cool end humidity 48%. He acts interested at first then does the head jerking back and hes' done. He has been eating f/t like they were going out of style. I have tried room temp f/t, med heated and hot, white and dark colored rats, jiggling and leaving it with no luck. Any one else had this problem?