Wierd ABS noise

[FLAT4MATT]

Is it normal for the ABS to make a sort of Psssshhhhh noise? I was braking fairly hard yesterday and hit a nasty set of pot holes/lumps. This caused the wheels to hop across the tarmac and the ABS kicked in. Everything worked as it should but instead of the usual (as in every other car i\'ve driven with abs) noise it made a dull psssh type noise. Bit like a BOV or air suspension / lorry brakes etc

This normal for an FD?