My husband called me his ex's name

Hopefully it is nothing but my husband called me his ex's name right in front of his kids. It wasn't like we were arguing or anything either. He just looked up the name of a movie he forgot and when he told me what it was called he said his ex's name. We've been together for 5 years. He called me her name in bed several years ago and it hurt. I feel silly to be hurt by it but it does sting because she calls all the time to say how much she loves him and misses him. We have to see her twice a week to exchange the kids. It's surely nothing, right?

I'm on clomid and it's just making everything so emotional right now for me. Would you be worried? I don't know if I should say anything because I think he thinks that I didn't hear him.