I have friends whom are zoo keepers looking after reptiles and I know they rarely have single sheds of snakes that size but they always are able to complete the shed un aided. I might suggest that perhaps a faulty hygrometer. Digital units are easily altered to read wrongly. Damage to cords, battery faults (low poor contact) dirt on the probe, dust, urine, any type of salt or conductive or resistive material on the probe even minute amounts will cause hight or low readings. (they measure the electrical resistance of the air...) I use high quality analogue ones as they are much more robust. It might be worth the effort to check the hygrometer for accuracy. Normally I'd suggest a salt test but this test damages digital units. You can buy a calibration kit from a cigar store to use. It might be cheaper to just replace the hygrometer with a certified new one.