S3 output plugin not releasing file handles fast enough

Log activity recently picked up on my system, and now it is holding on to several gigs of space even after it has uploaded the logfile to S3 and deleted it from the system.

I have my configuration set up to rotate the file every hour, but it seems to keep the file handle for several hours. Currently I'm just restarting the process to release the old files. Is there a configuration option to turn down the length of time it holds on to the deleted files?