Dead battery in certified used car!

Of course I test drove it. Was that a serious question or a jab? It was strange, and they said that “sometimes this happens when a car sits on the lot”.

And, of course I’m familiar with the warranty, which explicitly does NOT cover batteries, brakes, etc. I don’t think anybody does that.

The car started and ran fine for the 2+ months since then, so far as I could tell.
But now, with the new battery, it cranks significantly faster.

My question is whether it’s reasonable to expect them to honor a verbal agreement on a very specific issue.

"…I would chalk it up to lessons learned."
Which lesson is that?