Kinda hurt and confused

My bf and I have been together for 4 months so I understand, not that long.. him and his mom go to Gulfport every month to take bundles (she coupons and sells bundles)... since we started talking, he has asked me to go with them every time... the last time we went, his mom wouldnt look at me and now I'm not allowed to be at his house when she's doing coupon/bundle stuff. I havent seen his mom since the last time we went to Gulfport which was a month ago.. they're getting ready to go to gulfport again and he hasnt said anything ab me going.. I'm just kinds confused and hurt? I'm not sure what I did but I feel like his mom doesnt like me.. every time I ask him he says she doesnt have a problem with me but it went from "you're welcome at the house any time, if he isnt home yet just come on in, to me not being allowed to come over when she's doing it and I havent been to his house or seen her in a month... what do I do or say?😔