Discovered these while cleaning up my clinched lists and looking over my GPS tracks. I've found a possible route in the York area, and a possible route extension in the Lancaster area, both of which need further investigation.
The possible new route is "PA 892". Apple maps (which appears on my GPS tracking app) has it beginning at I-83 Exit 10, briefly goes west on North St to intersect PA 214, then turns north on Main St, crossing Lake Williams and PA 182 (along South George St), then ends where BUS-83 meets South George St. Google Maps shows the northern part of this as "PA 892", but Bing Maps and OSM do not show it. I have not checked photo sites or GMSV.
The possible route extension is PA 722. Apple maps shows it crossing PA 272, going south along Bushong Rd to Quarry Rd to end at PA 23. Google Maps does not show this, nor does Bing Maps (though Bing Maps doesn't show PA 722 along Oregon Rd either) or OSM. So it's likely that this one doesn't exist or is a former alignment that Apple hasn't updated.