Wet Cushion

We have a strange occurance with a cushion within our caravan and wonder if anyone can shed any light on what may have happened.

One of the back cushions in our Elddis caravan became wet at the end of last year. It was only wet on the front, so could not have come from condensation on the wall. The seat cushion itself was not wet and no water had gone down in to the bedding box. We brought the cushion home and had it sat against the radiator for a number of weeks, every time it looked like it had dried out we would remove it, but within 2 days it was feeling wet again. We have since had it sitting in front of a dehumidifier and "touch wood" after a good few more weeks it does appear to be dry, but has now got a very hefty water mark on the cushion.

The strange thing is we have no idea how it became wet in the first place. Does anyone have any idea what could have happened and why this took so long to dry out. We do not remember spilling anything on to it at any stage.