Advice regarding possible damp problem

Hi everyone,

I'm now at the end of my first season caravanning and in the process of getting my caravan ready for the winter.  When I was clearing out one of the lockers last Saturday, I noticed that the bottom of one of the struts felt damp to touch.  I had just washed the outside of the caravan so wondered if some water had somehow made its way into the locker, perhaps where the rim of the battery locker joins the van?  I've left the locker open all week and while it doesn't appear to have got any worse or spread further up the strut, it still feels damp to touch.  I've looked under the van and can't see any evidence of dampness underneath, however I'm concerned this could be the beginning of/ an indication of something more serious so wondered what others would do in this situation?  I've attached a couple of photos so you can see exactly what I'm talking about.

Thanks in advance,

John