It might be a small amount of corrosion that locks the shaft up.
This is common in marine turbo diesels as they tend to sit for a long time between use, ingest midly salty air and sometimes have salt water injected into the exhaust not far from the exhaust wheel. This is not usually checked though and most will free up upon the application of small load. This would have happened when you took the car out for a drive.
If it is a corrosion type issue as above that is locking it up I wouldnt really worry, if its not I dont know I have nothing more to add