I've seen batteries last 8 years, and I've seen them go in 2. When I used to sling parts for a living, I had a few training classes with AC Delco for my ASE certification. There's a bunch that can contribute to a battery lasting longer or failing sooner than expected, be it electrical drain from the car or a weak electrode in the battery that may have just passed the minimum QC when assembled.

This isn't to say that having work done to your car wouldn't cause the battery to die. But not saying it would either. It's always in the realm of possibility that it was a coincidence.

Speaking of batteries, had to replace batteries in both cars ('12 Focus, '13 Fusion) last year. Fortunately my wife has about 3 weeks left on the warranty on hers. Mine was the original that came with the car. Not mad, but they always seem to go at the worst times