Bad Battery?

I have a 2008 forester with appx 30,000 miles. Recently it has not started on two occasions. It will turn over and cough/sputter but not start.
Even though it was turning over I jumped the battery off my pickup and it started right up! Let me add at this time it (forester) was turning over fairly strong before I jumped it. Any ideas?
The dealer seems to think it's the battery even though it is only two years old. He says the new subaru batterys are "junk"....trying to be green has produced inferior batterys....less lead etc. Any thoughts!

I do not see a lot of bad batteries with Subaru. I do see a lot of cars that sit and only get started and run on occasion which can discharge and weaken a battery. Particularly before they are sold. I would assume it is the battery, a weak battery can cause a pcm to act nuts.