In your previous post, you mentioned that you've gotten over 6 hours of battery usage from your MB.
You do know that once your MB hits a certain percent when charging, it stops the fast charge system and switch to trickle charge.
There are even times that your Macbook is plugged in and will say fully charged but at 95%. That is normal.
Since your MB is sitll under warranty, why don't you just use it and worry about the battery 1 month or 2 before your warranty expires then replace it if needed.
Your one of the lucky ones getting over 6 hours with your battery. So don't worry too much about it.
If it bothers you too much, you can drive down to the Apple store and have them look at it if you wish.