From what I read here and elsewhere, 3 years seems to be pushing it for AGM batteries, especially in hotter climates. My wife got a battery at an auto parts store for $220. It came with a 3-year full (not pro-rated) warranty. Some folks above found them even cheaper.
Might want to have your battery tested by someone you trust if it’s been 3 years since delivery date. Hope you enjoy the car.
3 years in hotter climates…maybe. 7+ years here in the north.
I get 6-7 years out of a regular lead acid battery in the Northeast, probably longer if I wanted to push it. I thought AGMs lasted longer. What is the advantage then in a car? I’m using AGM batteries in the solar setup in my truck camper.
The warranty coverage tells you something about the lifetime expectations. 3 years pro-rated versus 3 years full coverage. They expect the AGM to last longer and they do. But nothing lasts forever 
FWIW- I’ve never replaced a battery in a car or truck with less than 10 years of service. Conventional batteries, nothing special. As such, those warranties mean nothing to me beyond cursory quality comparison when purchasing a replacement.
I took possession of my 2015 Sonata Sport in Oct-Nov 2014. Since 2015, Light use; most trips 1 - 5 miles between starts, occ. 17 to 35 miles. Good location for stores, mailbox, church, etc., wouldn’t you say? Houston, TX Just - Jan 2020- replaced OEM AGM battery with 25,000 miles at Dealership for $277 complete.