lvm archive and backup files not purging

I do hourly backups doing snapshots, and every time I do it creates files in /etc/lvm/archive. But lvm doesn't appear to pay any attention to the "retain_days" parameter under "backup" in /etc/lvm/lvm.conf, because I've got 9000+ files there, going back to 2012. Should I set up a cron job to purge them myself?

Here's the backup section of the config file:

# Configuration of metadata backups and archiving.  In LVM2 when we
# talk about a 'backup' we mean making a copy of the metadata for the
# *current* system.  The 'archive' contains old metadata configurations.
# Backups are stored in a human readeable text format.
backup {

    # Should we maintain a backup of the current metadata configuration ?
    # Use 1 for Yes; 0 for No.
    # Think very hard before turning this off!
    backup = 1

    # Where shall we keep it ?
    # Remember to back up this directory regularly!
    backup_dir = "/etc/lvm/backup"

    # Should we maintain an archive of old metadata configurations.
    # Use 1 for Yes; 0 for No.
    # On by default.  Think very hard before turning this off.
    archive = 1

    # Where should archived files go ?
    # Remember to back up this directory regularly!
    archive_dir = "/etc/lvm/archive"

    # What is the minimum number of archive files you wish to keep ?
    retain_min = 10

    # What is the minimum time you wish to keep an archive file for ?
    retain_days = 30
}