Macbook Pro battery capacity down to 85% in 3 months?

So I just got a Macbook Pro in July, because I had heard all these rave reviews from my friends and especially about the insane battery life. I needed a laptop that could run on battery power for 4 - 5 hours daily. So I went ahead and got it. Everyday, my Mac would come down to about 30 - 35 % of charge, and I would charge it to around 90 - 95% for the next day.

As the days passed by, I noticed that the full charge capacity had been dropping but I never bothered thinking that it must be normal battery behaviour. But to my shock, it's been only 3 months and now the battery capacity has come down to around 85%. I have about 53 charge cycles on my machine.

I called Apple the other day and told them about the situation, and they seemed friendly and said that I shouldn't worry as long as there's no warning to get my battery replaced. But when I asked if the battery replacement would be covered in warranty, they couldn't give me a straight answer and started saying vague things such as, "it's a consumable part, so it's bound to decline" and "your warranty extends till July of next year, so you need to bing it to a service centre so that we can see what we can do."

I looked around on the Internet a little and found that Apple doesn't always cover battery replacement in their warranty, so I am at a loss to what should I be doing. If they won't replace my battery, I might have to stop carrying my Mac around in places where I can't charge it.

Please help on what should I be doing?