"unauthorized access" error

I have not restarted my validator, and it had been running fine for the last several days, but today I started seeing this:
INFO [11-26|04:33:14.004] Commit new mining work number=520929 sealhash=256dfd…6a6578 uncles=0 txs=0 gas=0 fees=0 elapsed=313.789ms
WARN [11-26|04:33:14.004] Block sealing failed err=unauthorized
ERROR[11-26|04:35:37.725] Failed to decode message from payload address=0xFBd7a1Bf03DE29422775997C0974eDa4DE2e7c30 func=handleMsg cur_seq=520953 cur_round=0 err=“unauthorized address”

Any ideas?