Cam was purchased about a year ago.

Lifters were definitely spinning before the accelerated wear started. I went to extra effort cleaning out the bores and test fitting the lifters at assembly. Judging from the wear pattern, it even appears it continued to spin after the wear started. It would have wiped a lot sooner otherwise. I'm pretty sure botched preload was the culprit.

Picking the next set of lifters right off the proverbial tree. Ordering direct from Topline Hylift.