Stuck or gummed up rings can be caused by infrequent oil changes, cheap oil, lots of short trips without allowing the engine to reach operating temp, regular oil changes at a quick lube where they fail to change the filter etc.
Sludge and varnish and other goodies build up in the ring grooves preventing them from sealing properly. rings depend on a certain amount of flex and movement ( very slight)to seal . when they get gummed up that flex is inhibited allowing gasses to pass by.
Low compression on one hole is usually either a stuck ring or leaky valve,or head gasket blown to the side, but with no other symptoms( it would run like trash if you had a leaky valve or blown gasket)it would be a good idea to clean up the rings and see what happens.