LP should be checked for all the time - as it's very common.
Do a search here for Luxating Patella and you'll find lots of stuff.
LP doesn't fix itself, it doesn't get better over time. Sure there are supplements to take, but nothing is proven to be a 'sure fix' - it may aide it, or at least we hope it does.
The problem with leaving LP alone is that every time the patella (knee cap) luxates (slides in and out of it's groove spot) - the cartilage is slowly being worn away. This cartilage can never be replaced, so at some point there may be bone rubbing on bone - now that's gotta be painful.
Now even though they don't act like they are in pain, they very well may be, b/c honestly we would never really know. They can't tell us it hurts just a tiny bit, they just deal with it right?
After Roxy had her LP surgery, boy oh boy, she was a brand new girl! That's how we knew she must have been in pain or at the very least very uncomfortable
I hope that help you.