EFS 17-85mm noise

I've just bought a EFS 17-85mm IS lens and when the IS is turned on it makes a sort of noise other than the auto focus noise. I've never owned an IS lens before so is this normal?

It's the IS motor spinning up. It's normal.

Ok thank you. Just wanted to make sure as it's second hand and don't want it to brake in a month or two.

Is the noise very loud or does it sound grinding? The IS motor should sound like a very quiet almost humming type of sound. Some people can't hear it at all it's usually that quite.

I wondered the same when I got mine for the first time, but yes, its just the IS.
Here is a video clip, it is terrible, but at one or two points you can hear it focus, and the noise of the IS starting. 3:44 Clip
At about 1:48-1:52min then again around 2:00min you can hear what I think it is you are hearing.
http://www.youtube.com​/watch?v=uABL_uChn3k

it should sound like a very faint click then a humming noise... not so much a click but similar.