It takes alot of heat to cause these non-stress relieved barrels to warp (300º F or more) which is much higher then firing the rifle will yield SO the most likely cause of barrel warping is a bore which is not concentric to the O.D of the shaft or barrel. The different thicknesses will cause a change but since this temperature is low I would expect the barrel to go back to it's original shape. If you only fire shots out of a cold barrel you would not notice it walking.
Well I was wondering, they used to "straigthen" barrels. I have seen pictures and a machine at Springfield Armory, I think I have seen pictures of sporting barrels being straightened. How does straigthening effect a barrel?, are there internal stresses that show when the barrel is fired and as it gets hot?