I don't think your making a big deal out of this, I would be upset! That is a very short session in my opinion, and I would ask her about it. Especially since you are paying out of pocket for it. You could phrase it nicely, and just ask for some clarity about how long the session is because it seems to vary. Its your right to know what your paying for, and I would start having a major resentment if I was paying for a shorter session than others are getting.