You put these on dry right before bed, correct? At least the socks and the thermal top. If they were the same ones you wore during the day then they would be wet, even if you didn't think you were sweating any. Air mattresses are not good insulators. At least you had a foam pad on top of it, but I'd recommend using just a ThermaRest style pad (air mattress stuffed with foam inside, basically). If you pad is not full length, wad up clothing and other gear and put it under the foot of your sleeping bag. Mummy bags are at their warmest when the hood is drawn up and snuggled around your face. The inside draft collar should be tightened around your shoulders as well (if you bag has one of these - doubtful, for a bag used in Texas that left you cold in the 40-45 degree range - you may not even have a hood on it).

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Same thought, same time, as obmeyer. On the dry socks/top. We were both typing and posting at about the same time.
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