Starter mystery find

[V30 mongo]

First off: 1988 V30 CC 6.2 diesel sm465. On trying to start the truck ,the starter "stuck". Trying to push start failed, the engine was locked up. After removing the starter the truck push started. Later on, while replacing the starter a washer was found in the bell housing with gear marks. The washer must have been caught between the starter and the flywheel. The washer looks like a 1/4" or 5/16". Question? Is there anything in the bell housing/ clutch that uses this type of washer or did it just "find" it's way in there. The truck starts fine now. Will it be ok or should I have to remove the transmission / transfer just to check for a missing bolt and washer?