Matt these are all smaller snakes? Do they spend most (all?) of the time on the cool side? It is possiable that the hot side is a touch warm for little snakes they do not need as much heat as adults and with the frequency of thermometer error I'd suggest trying a few degrees drop on the hot side maybe down to 88º and give them some time and try again. Small snakes in my experience are ready and willing to eat often and aggressivly. I might give the temps a shot striking and dropping could be temp related or prey temp related (I measure mine to 100ºF give or take) or security related or just snakes being silly. If you are having issues try a temp drop and see, if that doesn't work try something else.