Pop up 👀

So this guy and I have been dating for about 8 months and he has 2 kids with one woman. Their kids are currently out of town with his mother for the summer. While I was at his house she popped up. I overheard her ask “do you have company” he said yes so she said I’m sorry then left.

I don’t have kids so I’m not understanding why she needs to come over if the kids are over 1,000 miles away and she has his mom’s number to communicate with them. Am I overthinking or overreacting for feeling some type of way? How would you address the situation. (No negative/disrespectful comments please ‼️)