Blue thermal stone in backpack causes overheating

Playing A Cold Reception as Wheeler, placing a thermal stone in the backpack (while worn) causes overheating. This seems to occur only after the first winter (possibly just because the stone needs to heat and cool once). Body temperature seems to go up by about 1 degree per second; removing the stone cools at about the same rate. Placing the thermal stone in the regular inventory works as expected. This has been seen in multiple saves.