Mom jealous of MIL

My mom and I have never been super close but we have a good relationship. I don't consider her my best friend like some girls and don't really go to her for advice or just to talk. I get along pretty well with my MIL and she's a great person, very friendly. We don't hang out every weekend, but I feel like I could go to her if I needed. My mom seems to be very jealous of MIL and it really annoys me. It's as if she doesn't want to be friends with her just by comments she makes to me. Never anything very blunt but I'm getting that vibe from my mom. Maybe if my mom was more open to MIL it would actually make her and I closer..? She's being kind of selfish in my eyes. I would love to be best friends with my sons MIL in the future!! So I just don't understand.