The oil filter says April 19, but that was just the day the oil went in. This thing didn't get any mileage until what... June/July? Of course that was the shittiest concoction of miscellaneous oils I had laying around at the time. I just put the barely used 0W-40 from the HellKitty in it for the Winter cold starts, when it gets bumped out into the elements because I need the spot to service the Mrs. truck or the TBSS.
If I had to guess this is the start of a cam/lifter issue.
But, yes - the 4.8 needs to get finished.