I had the same issue with my 8x32 Discovery WP PC. After over a year of use it started happening. Eventually, it became so bad, that the hinge was absolutely loose and just closed itself in a couple of seconds. So today I have taken it to the shop where I bought them (Oryx, in Barcelona) so they can send them to Opticron for repair (since they're are covered by the guaratee).
As a general comment, I'm pleased with both the weight/size of the binos and their optical performance, but the built quality if far from perfect. After a few months of use the rubber cover of both eyepieces became absolutely loose (to the point that the entire rubber piece falls of when you uncap them). And the rubber cap that protects the hinge also fell off. I have a pair of Minox of lower price/range which I've had for longer and they're just as solid as the day I bought them.
Furthermore, I bought an Opticron MM3 60 travelscope which I also had to take back to the shop; after a few months, the main lens (the biggest piece) became loose (I noticed the scope was producing a clunky noise). Fortunately, the shop was able to repair it in less than 24 h (I hope the waterproof properties remain unchanged).
I've bought two Opticron products, and both have needed returning (for lesser or heavier issues). Maybe I've had bad luck with both Opticron products, I don't know.