Mine's been doing the same thing since it got cold out. Most significant from stop-1st and 1st-2nd. I have a feeling it might be subframe bushings wearing out and hardening up some from the weather. I suspect the natural torque that builds between the subframe and the frame as I shift is demonstrated in the creaking sound. The higher gears don't result in as much torque "change," if you will, and have less apparent creak. At it's worst it sounds just like a slow, creaking old bed or door at your favorite halloween haunted house. Hopefully this is all it is... hopefully. Any thoughts?