I'm pretty sure they won't do anything until it falls below 80%. Once that happens, take it to the Apple Store and they should replace it for you if you're still under warranty. But going in right now probably won't do you any good.
Your battery health will fluctuate up and down over time. It's not a straight-line decline. The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.