Snapshot S3: Backup saves to S3, but is restored from local copy

When I take a snapshot with the destination set to S3, it appropriately saves the snapshot to the S3 instance. But it also leaves a local copy, and the local copy is the one used to restore the backup. If I delete the local copy, I'm no longer able to restore the backup even though it still exists in S3. Is this how it's supposed to work? Thanks.