I am 13 and still suck my thumb is that normal?

i suck it when i feel threatened and before i go to sleep....i didn't suck my thumb when i was little i asked my mom and she said that i never even wanted a bottle when i was little i suck my thumb at school and if anyone asks then i tell them that i hurt my thumb (which normally works because i am a klutz) but i was wondering if that seems normal because i already have braces so im not worried about the teeth thing but my mom doesn't know i suck my thumb and i just told my BFF about it recently but she said that i should stop.....