Lines b/c of cold? Oly 50

[ander75it]

An old problem that I have had with my Oly 50: when the temp goes under 0° (Celsius) in the upper part of the image I often find lines such as those in the attachment (I chose a very severe case to show what I mean). Usually it's not so bad, especially if I keep the camera close to my body before shooting, but it's annoying, even though it shows less in prints then on the monitor. Now, I know the camera is rated for operating at 0° or more, but other cams of friends do not have this problem. Has anybody ever seen this?

This behaviour has been constant throughout the cam lifespan, and is not related to its current problems (if interested see thread in What camera I should buy / Is Canon S2 IS good for me).