Young horse back leg joints click?

I have a five year old Thoroughbred gelding that's always had clicky joints, more so in the winter. We have never had lameness issues, swelling or heat that was associated with this. He never raced, etc. We are starting jumping and he seems less clicky and as if he's stretching more. He has front shoes (doesn't stretch at all without them). He does click a lot if he's off of MSM. I'm just trying to do some research as to what it might be, if it's a big concern and if so what should I do? I know I myself have clicks from joints that do not and have not ever bothered me. Is it just some weird thing? Opinions welcome, please be polite!