Its possible that it had a carboned piston and then a hard run or a cleaner burning fuel or hotter condition, or as Stewart said, a small coolant leak, washed the carbon off and the loose carbon caused the ring wear. The sleeve will wear faster than the nicasil, too. You might want to get back to a stock cylinder so you can run a tighter piston tolerance.
Sounds good on the vid you posted. I see you needed boots, now. Did it fix the compression readings?