I had a motor with an overlapped oil control spacer once. It wore a vertical line in the cylinder much deeper than that. Do a leak down test on all the cylinders, and see if that one is sealed well or not.

If it has the same leak down rate, you could keep running it and see if it gets worse. Or, you could always pull that side's head, pull the piston out, find out what is going on there, scuff the bore with a scuff pad to de-glaze it and put a fresh set of rings in it.

1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)