Chameleon Licking My Brother?

I was wondering. Why does my chameleon lick my brother? She doesn't lick me or anyone else. What she does is, she stops, puts her head down to my brother's skin and licks him. It isn't repeated licking but randomly. She's a Fischer's chameleon and about the size of 3/4 of an average envelope. Is this normal? My Veiled chameleon didn't do this. Is there any reason why she's doing this? Should I be concerned? Please answer. Thank you.