Octy vRS Lifters - information needed

For the last 8 months my Octy vRS has made a very loud mechanical sound on start up (not the usual sound). The dealer has changed -

Starter

Secondary Air Pump

Cam Chain & Tensioner

New set of hydraulic lifters.

They say one of the lifters was soft.

The car has only done 30,000 miles. Would you expect a fault with the lifters at this mileage? Would one faulty lifter really make that much noise?

Any comments about lifters would helpful.

(I haven't collected the car yet, so I don't know if it has cured it yet)