I have, and she hasn't responded, but I don't think it bothered me a whole lot. Usually, by the time the next session rolls around, there are more pressing things to go over. There was one regular, non-apology email that she didn't reply to that bothered me (she doesn't reply to all of them, but this one had been important to me), so I asked her about it the next session. It turned out that her reply was in her draft folder and she thought she'd sent it; as I was leaving, I asked her to resend it, which she did. Even though she'd told me what she had written, I still wanted to see it.