Yeah, aground down cam lobe is often a sign of inadequate lube.When i bought my early 2000ish '425' polaris a few years back, the guy i bought it from (he was a polaris dealer mechanic) said not to let it idle too long, he said that they don't get good oil to the top end at idle and will take out the cam if they sit and idle. He also said they are real picky about frequent oil changes and using the OEM polaris oil.
I dunno about the last part, i run it on Rotella just like everything else on the farm, but the idling thing sounds legit.
Nice thing about finding something like that, its probably the only thing wrong with it.
Also common if the oil level is allowed to drop too much.