What would you do if you baby all the sudden?

My son will be 7 months on the 12th and the other day I had him on the floor playing in his room and my 2 year old gave him one of his pacifiers that was on the changing table. He never had any interest in them before but now he likes it, he is nursed and very attached to the and usually has to nurse to go to sleep but tonight he just took the pacifier and layed on the couch and fell asleep by himself. So would you let him have it or take it away? He doesnt want it all the time, hes teething so most of the time hes chewing on it and when he gets sleepy or fussy he will put it in his mouth and suck away! I want him to be happy, what would you do if it were your baby??