Why did my boyfriend say another girl's name?

Okay so we went out the other night and when we came home, he was passing out, so I started messing with him to wake him up, and he was like "oh yeah" and then I was like what's my name? and he's like Jenn, and I go WHAT? and he goes Jenn, I flipped out on him and am like what the hell is going on here? and he the next day says he didn’t say it and doesn’t remember. It pretty much hurt me. And this girl I found out is a bigger set woman who he has told me about before from work, and that he thought she was nasty and so on. And this other guy he works with says yeah she is nasty and so on. And I’m like was he just dreaming about work, and that she was in it? But at the moment I was touching him why did he say her name? Should I just brush it off? Or should I be worried?
Why did my boyfriend say another girl's name?
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