MIL and my son problem

So

Ok idk if i should say something to my MIL or have my husband speak to her. My son is 19 mths and at times my MIL wants to hug and kiss him all over, for the most part he’ll play along and not complain but at times he’s had enough of her and starts screaming and crying for her to leave him alone. I tell him it’s ok that grandma is just playing. But honestly it’s bothers me that she doesn’t get the hint and doesn’t leave him alone. And if she does let him go later she’ll act mad and completely ignore him and kind of pushes him aside so that he leaves her alone. For the most part I ignore it but it really gets to me when my niece and nephew are over, she starts acting more loving to them while my son follows her around trying to get her attention.