The mark is in the form of perfect parentheses "( )" in the middle of the screen (not related to the focus brackets). It is not visible in recorded images. This is the 2nd E-PM2 that shows this (both from ebay, the first I returned and got this one from a different seller). The first seller said afterwards that it was a drop of liquid on the sensor, but I doubt that both cameras have exactly the same size, same shape caused by a random drop of liquid). The camera appears to perform perfectly otherwise. Any idea what this might be? Many thanks for any suggestions. Below is a picture of the screen with a piece of white paper in front of the lens.