What you describe could indicate that the file was damaged before it crashed. It can be difficult to determine if file damage is the result or cause of a crash.
In either case, I'd run a recover on this file and see what the recover process reports.
After working fine the whole work day, the database crashed again when I logged in yesterday evening. Also, a development database decided it was damaged in the middle of the day yesterday even though it hadn't been touched for a couple of days.
I'll see if recovery tells me anything useful this weekend.