Battery looses 1% every 3-4 minutes...

Just bought a 13" Macbook Air (Early 2015 Model) 3 days ago! The first day, I charged it till it reached 100% and in my opinion I think it was working okay, battery seemed good.

Since yesterday, I noticed it looses 1% every 3-4 minutes. I started using my computer at 7 pm-ish today at 100%. So far I just browsed on the internet, mostly online shopping. It is now 8:45 pm and my battery is 74%!! 😟

A lot of ppl were saying it needs some time to level out but I'd like to know if its normal or if this could be an issue?

I just updated to OS X Yosemite 10.10.5 just a few minutes ago but I noticed this issue before the update.