Steering moves the footwell carpet!

[PaulHere]

When I turn the steering wheel on my 60 reg Fiesta automatic there is a strange undulating sensation under the carpet in the drivers footwell, is this a problem - should I be worried, it's certainly weird?

I imagined under the carpet lining there would be steel floor.

[TomsFocus]

The floor is steel under the carpet and sound deadening, but the steering column runs through those and a rubber grommet so it can be felt.  Is it only with your left foot quite far forward or anywhere in the footwell?  I find my left foot catches the steering column in small cars (106/206/Fiesta etc) with the clutch down which is an odd feeling but it's purely down to squashing all the controls into a small space, not an actual fault.