The last few times the temp has dipped below zero, the ABS light comes on after a few seconds of driving. No other symptoms and the light clears once the weather warms up....any ideas? Should I be concerned?

 

Check all the connection's at the two front wheels and the one on the rear at the top of the diff. Disconnect each one and make sure there is no dirt. If you want to know which one it is, it must be read with a good code reader, no autozone or superchips etc. Also check brake fluid level.