Yes exactly.....mine does this maybe 1 outta every 6 weeks or so..has trouble starting on the first crank..My battery is also new from April.. It could just be one of those freak things that no one has an answer for. It makes me nervous though..

What do I do with the old (bad)battery?

Primetime- Will keep u post on my battery.

as far as i know autozone cannot accuratly test the battery in the 4.4 - the 3.0 not 100% sure on that. anyhow i had the same symptoms, the engine would crank and not start, and sometimes have nothing happen. i switched to the other key and havent had the problem since. maybe the key is going bad. i think ts about $150 for a new key.

should be given to autozone/wherever you bought the new one. they'll give you $5 back for a core charge usually.

U can give the old battery back to autozone and i think they give you like 10 bucks for it or something....I beleive the old battery is referred to as the core.