Sasha should recheck file expiry before deleting expired file.

There can be a significant gap between when Sasha scans files and regards them as 'expired' and when it actually deletes them (a 7 minute case was seen).
Sasha is unaware if a file is read during that time and will go ahead and delete it, causing confusion.

Sasha should re-check to see if the file hasn't been touched before actually deleting it.