My 2 year old has a fixation with rubbing skin

My son is 2 years old and he rubs on ladies legs and backs. I think it started when I was just pregnant with his brother cause he would rub on my stomach all the time, I thought he was just bonding with his brother but now that his brother is here and he still tries to rub on my stomach. I certainly feel it is something else. he rubs on my legs when I come out the shower and sucks on his tongue. Is this normal?? I can understand that this may be soothing to him as I did suck my thumb and rub on a cloth until I was 30 years old, but is this something he will get over soon??