Baxi 105e clunking noise every time I turn a hot water tap off?

Baxi 105e 4 years old. Whilst the boiler seems to operate properly, every time you turn off a hot tap in the house, the DHW valve appears to snap shut very noisily which transmits through the pipes.

When you watch it operate, the valve spindle is obviously free and the second the micro-switch operates, it quickly shuts with a clunk.

If it's normal - fine, but I would have thought it should shut more quietly.
Could it be something to do with the diaphragm/spring perhaps?