Did you park it with the handbrake on in damp conditions?
------------- Love a lot. Trust a few. But ALWAYS paddle your own canoe!!
Minds are like parachutes:- They only function when they are open!!!
Those who talk don't know.
Those who know don't talk.
Usually due to age of brake linings. Many caravans do little mileage so brake linings could be yrs old. Nothing lasts forever, I suggest you get brakes serviced with new linings fitted all round.