Mummy tummy

My 3 year old first born baby boy is obsessed with my 8-month post partum mummy tummy...he would grab my exposed belly while i breastfeed his baby sister. It can be too much hassle since i have to have him around clinging to me for as long as he wants to snuggle my tummy...it can get really overbearing...aaaarrrrggghhh...is it normal???