It took forever for me to be anything but "happy" in session. I didn't trust anyone with my emotions, it's still hard for me express any negative emotions (anger and sadnes). I think it's good that you trust your therapist enough to do that - even if its just a little bit.

I consider the sessions where I can actually cry to be the good "hard" ones. Otherwise I hide behind my mask and pretend nothing bothers me. *sigh*