DD does this all the time!! DH thinks its funny. But she keeps me awake at night cause she is always grabbing my nipples when she feeds!! OUCH!!
she does it when we are out and she is tired, hands in the bra before i can stop her!
A friends DD who i used to look after alot years ago who was BF till 2+ would stick her hand down my top when she was tired. At the time i found it really wierd and stopped her doing it, but now i can see that it was just a comfort thing and actually quite a compliment as she obviously felt comfortable and safe enough with me to think my BBs could be a comfort like her mums.