While changing my oil I noticed one of my coolant hoses off the heat exchanger was collapsed while not running. Once the engine warmed up after several minutes, and I assume the coolant warmed, the hose went to it's normal shape. It is really cold out and I might not think much of it if the other engines hose weren't completely normal in shape under all conditions. This seems like a vacuum issue to me somewhere. Anyone else have this problem and solved it, or is it a non issue? Maybe a faulty check valve on the radiator cap?