We've been seeing these in the logs for roachtests:

I201007 12:20:23.504036 77953 sql/catalog/lease/lease.go:2053 ⋮ [n1] refreshing descriptor: 4294867296 lease failed: descriptor not found

This one is from kv/gracefuldraining/nodes=3. I've also seen this on some of the tpcc schema change roachtests. We should figure out what's going on here.