ASR, what's it feel like?

[lycanthrope]

Hi,
Accelerating away in first gear, if I put my foot down a bit there's a sort of rumble like feeling from the back end for a split second, no noise though. Is this ASR working or something bad?
Thanks.

 

[LostKiwi]

ASR cuts power to recover grip and when active will flash the ASR light on the dash.

 

[lycanthrope]

ASR cuts power to recover grip and when active will flash the ASR light on the dash.

There are no lights, I've been doing a little digging and I'm now wondering if it could be the flex disc?