You should probably have an alignment done, but I don't see how the alignment would change after driving a few miles to warm up... temperature seems to be causing it since you said it's worse in cold weather... so ya I'd have your tires re-balanced.
2008 2dr JK
Mod List (So far)
OME HD Lift with NitroCharger shocks. JKS front and rear adjustable trackbars. 33" Toyo Open Country MT's on 18" XD Rockstars. JKS Quicker Disco's. RockHard 4x4 Oil Pan Skid. Shrockworks Rock Sliders. Woods SS relocation bracket & evap relocation bracket. sPod switch panel. Tuffy Security Cover
-Drive it like you stole it-