Journal files missing in the snapshot


I have acquired db.fsyncLock() on the secondary node of the replica set and collected the list of files and folders in the MongoDB dbpath. Post which I take a lvm snapshot of the dbpath volume and db.fsyncUnlock(). But one of the journal file is missing in the snapshot. This was part of the list collected before snapshot and there is a mismatch.

How to overcome such situation? And what has caused the file to be missing although lock was acquired.