Beep sound?

[Polofiesta]

Just installed the latest software update with the thunderbolt stuff or whatever. I have a 13" mbp 2011 i5. After it restarted it made a beep sound and the screen was black and the white indicator light was on. Then it went to the apple logo with the bar under it filling with grey. Everything started normally and so far nothing is wrong but what does that mean?

 

[mdnz]

It's normal. If you read the information that came with the update you'll actually reaed that it's supposed to do that.