Weird charger problem...

I was wondering if anyone else has this problem, maybe its normal.

Basically i was watching a 1080p trailer on youtube and it sounded like a hard drive was working really hard (i have an SSD, so it shouldnt be). I turned off the youtube video and the noise disappears. Turn it on and it comes back. I finally traced it back to my power brick after a few minutes.

So my battery makes a lot of noise, annoyingly loud imo. Is this normal? I feel like i may be back posting tommorow in one of those "my MBP caught fire" threads...