Loss of accuracy

After a lot of pellets going downrange, I got my wildcat sniper shooting very tight, consistent groups at 50 yds. and not wasting a lot of air.

Then for some reason the groups started opening up and POI dropping. I near went nuts trying to find out what the hell was goin on as I had not changed anything.

Skipping the details, Found the compensator had unscrewed some, I noticed it by seeing a couple exposed threads. Screwed it back tight and that rifle returned to its normal shooting.

that's all I did so that must have been the problem. Has anyone run into this before? Don't know how it got loose, gremlins in the garage?

grump