My boxer had a cruciate repair last May and made a good recovery after a second op to remove the graft that had slipped - the knee was stable though.  The vet said that he would probably limp for a good while after, possibly forever.  George has been doing well and only limps after a good run if he has been lying down but this soon goes away.
However, he has been reluctant to weight bear through this leg over the last few days.  He will use it when out on a walk.  It seems unlikely that he has reinjured his cruciate as the vets said it was a very good repair and had healed well - what do people think it could be?

He was at my parents last weekend and I think he may have hurt is knee there escaping out of the kitchen so I was planning on restricted exercise over the next few days to see if it resolves.  If not then it looks like another trip to the vets - he has done this before and it has resolved so I don't want to take him unneccesarily but will of course take him if it doesn't get better.