Yes, my son also had the same behaviour around 1 year old. I think they are curious about this only without any meaning. But you can tell him "stop doing this" because 何B仔 is for 小便. My son had stopped doing this after 1.5 years old.
my son is now 7-month old. he also plays with his penis whenever i change his diaper or give him the bath. i just wonder whether it is itchy but it never gets red. so i think it's a matter of my son's habits. i have been trying very best to 'tell' him not to play with the penis again.