What would you make of this

So I am hesitant to write this but it’s bothering me. About 4 months ago I was working full time (on weekends) and my husband would watch our three year old daughter while I was at work. One day my sister popped over, she was in the area and didn’t realize I worked only weekends. She was playing with my daughter and my husband got an urgent work call and had to go to the office. He asked my sister if she could watch our daughter for about 2-3 hours, she said sure. So during that time, apparently my sister invited her boyfriend over for lunch. She left to pick up the lunch and I am pretty sure left our daughter with her boyfriend during that time. This part I am not 100% sure of but what I do know is her boyfriend acts very rude toward me the last few months. He has never been friendly or cordial around me and I get strange vibes. I am sick of worry that he potentially was with my daughter alone even for twenty minutes. I don’t want to ask my sister if she left my daughter alone with him because that feels like a loaded question and I can see her getting super defensive calling me crazy, etc. But I can’t figure out why her boyfriend acts so hostile toward me. Does he feel guilty or entitled? We are seeing them on Thanksgiving and I’m getting anxiety about it. Hoping it’s nothing but I just hate this feeling that something went wrong and I can’t do anything about it.

Edit: thanks for the feedback I will ask her if she left her alone but I could just reading into his behavior as he also did lose his dad to cancer. I just hate those types of situations like fear of the unknown and also hate to be accusatory like that but my mom antennas are super hyped up all the time.