Hi Tim,
It sounds like you made a connection with yourself, whether that be physical or emotional. I've had similar experiences, especially when first starting yoga. It's a beautiful thing and I still have them from time to time. The asanas open the body. So whatever area of the body that has been really opening up for you, perhaps brought out some stuff. I would just listen to your body and now that you have the awareness of your feelings, observe the sensations while you do yoga if you can.
Enjoy the journey,
-Liz

It definitely happens. I am not enough of a student to be able to explain it, but I know it happens. I have cried during yoga class, and one time afterwards... after shivasana, when I was in the hall putting my shoes back on.

God I love yoga.

Your in your body, your body is happy.
Now remember that anything that makes you feel that you are not whole, vibrant and complete is a Lie.
J.

Tim, our mental-emotional state is reflected in our musculature, and really there's no influencing one without there being an effect on the other. One fellow I study with regularly cautions the class when we go assume certain positions or when we perform various pranayama techniques followed by pranayama, and tells us if we're effected in certain ways during the practices that we should just lie down and relax. As you become more sensitive to the connection between the physical and emotional what you are describing will become more commonplace with respect to your practice, though initially, admittedly, these flows of energy coursing through us can produce 'tremendous feelings'.