its unlikely its too cold or there is too much nite time drop. they are quite comfortable in the 60*s, and in the wild, are often found above 3000' elevation, but they do like to bask, and occassionally they will even seek out more heat than is good for them (if available).they mostly like to utilize the upper 30% of the cage. thats why it is important to have your basking location/tempurature,and basking light/wattage/ distance/ climbing stucture, all dialed in. the highest basking temp i ever offer is 82* but it is on all day. cage crawling isnt that unusual, probably just a little antsy, or even hungry. i would be more worried about normal looking eyes and urates . i think they prefer to climb on actual climbing structure given the chance. it could just be that he is trying to get to the basking spot that he wants, which isnt necessarly the same one you have chosen for him. not to be critical, but if you look at the photo the upper part of the cage is really quite devoid of comfortable climbing structure, (and no the curved cord or vine or whatever it is doesnt count). there is no place for him to get comfortably on top of it, i think he might be more comfortable if your were to re-think the top of his cage structure and possibly remodel so that he has multiple prime basking choices, if you do i think he will probably learn to spend more time basking than cage crawling, jmo