Not shocking. I mean the second the charger is gone it does start to drain. You may want to wait a few days, and a few charges, to see if it changes.
Also, I would monitor how fast it drains below that 99. Some just drop instantly for the first 1% where as after that they react normally.
Additionally, check what you have running. Even if you didn't open anything, there can be things running in the background the second the computer turns on and gets to Windows. That will drain things faster.
Should it continue, and bother you, then take it back and have them exchange it for another.