Tom it looks like a cherry eye,it doesn't bother them ,so there is no need to rush to the vet ,Lily got hers at 9 weeks thrugh rough play and Shy "clawing her" (she claws everything as form of entertainment and pointing-for scent training my fault i taught her that)if you have a look through my pictures 99.9 % got a cherry in them from very beginning ,we tried to massage ours back but i popped out next day-bigger and ee couldn't massage it back in place , vet gave us eyedrops that were antibiotic and anti inflammatory, we waited until lily was 4,5 months old to do the op ,but from what i noticed most members waited to perform the op while dogs where neutered ;-)