Touching a woman's pregnant belly

I'm not pregnant again yet, but the topic came up at the in laws and I said that I don't want people to touch my belly when I get pregnant. I'm not a touchy person and I don't really like to be touched. My mil says well that's going to be my grand baby in there so you'll just have to deal with me rubbing and touching your belly. Am I the only one who feels like she shouldn't touch my belly if I stated and stressed to her that I won't be comfortable with it? Or should I just suck it up since she's the grandma?