worrying

Hi All i was cleaning my bike at the weekend and came across something that concerns me greatly, Has anyone else had a similar find??

Has anybody has this happen to them, whilst going down the gears my bike seems to be going into neutral, it doesn't happen all the time but I've never had a bike when it's done this before. I wasn't sure wether this was something the RSVR's had a bit of a reputation for but its certainly caught...