I disagree with you on this one...feeding a young snake an appropriately sized meal every 5 days, which is what the OP said he did, is NOT powerfeeding. Powerfeeding is inserting a second prey item into the snake's mouth as it finishes swallowing the first.
If you think about it, in the wild there are periods of time when prey is abundant, followed by times when there is less food available. Snakes are designed to eat alot when its available and fast when its not. It's also normal for subadults to go off feed, and it's fairly common for temp drops to trigger this in ball pythons.
Also, I'd stay away from gerbils. It's going to be a huge pain if the snake imprints on gerbils and since he's in no danger of starving to death there's no reason to try them. Gerbils are also much more aggressive than rats, so feeding them live is a bad idea...