My crested gecko bit me?

this has never happened before!? i was just handling him as normal, and he just leapt across my hand and bit me on that flap of skin in between my thumb and pointer finger. why did he do that? there are two possibilities that i can think of: one was that i was sweating and i had not washed my hands before picking him up. the other is because a week ago i had just given him his first cricket and he thought that my skin was a cricket. i have been not taking him out as much...maybe once a week. any advice? why did he bite me?