Mention it to him, but don't pitch a fit. It's what he was used to. Doesn't mean he wishes it were her instead of you, and it's hard to control your tongue when sleeping.
If he calls you by her name when he's completely awake, then you'd have more reason to be upset. You could always reply, in his ear, I love you too Bob (or some other name, that is not your husband's). If he awoke, you two could have a good laugh, and snuggle up and go back to sleep together.