That's what I thought too.Orphaned attachments are already cleaned up automatically. An attachment like that is likely attached to a post that wasn't made. It will be cleaned up (after 24 hours I believe).
Ok. Thanks!Running the cron will only remove files that it thinks it should remove. If it removed every file that related to an in progress post, you have the potential of composing a post while the cron runs and losing your attachment silently.
Check back in 24-48 hours to see if it's still there.