Might want to check this thread for a similair occurence. Not a real fix but it might be worth a shot. From what one of these guys says worked for him I'd try a hair dryer to heat up the possible freezing and a drive down the block. Shouldn't hurt much for just the 1 block. If it works, problem solved (for now at least). If not then you've only lost 15 min or so.
Also, backing it out of the drive might help release it. I've had a similair thing I dealt with on the SHO with a sticking caliper though. When it was really bad it would drag the tire in first but if I put it in reverse I could free it up with a couple feet of going in reverse.
http://www.rothbuilt.com/GatewayDSM/MBoard...ge=8966&forum=6
Sounds like the line froze with the recent cold weather.