Thanks everyone. This is my first breeding season, and I got a little freaked out when I was cleaning cages and realized she was most definitely building. I thought she was glowing, but I was trying to convince myself I was imaging things.
I don't know exactly how old she is. I got her in June of 2011 and she was already ~400g and she was sold to me as a 2010.
She really wanted to be breed this season. She was tail wagging whenever another snake was put any where near her (even if they were female).
She's not skinny by any means, but she just seems so tiny compared to the females I was actively pairing all winter.