I think it's probably wise to avoid the phrase countertransference and just talk about what you observe or sense from her. I remember once getting sort of upset/unsettled because my T seemed off in session and I didn't know why (I do tend to personalize things). I brought it up, thinking she was uncomfortable or feeling negatively toward me, and she admitted that she was feeling tired that day. It made perfect sense for what I was perceiving, so I was able to accept her answer and move on.

I guess my only other question is how you would feel or respond if she doesn't know what you're talking about or won't admit to it. Definitely not a reason not to ask about it, but something to consider before going in, I think.