Relay clicking noise explanation ?
 

So I took my 2003 A6 Avant 3.0 to the dealer for a relay clicking noise coming from behind the left side of the dash near the windshield. The dealer informed me that the clicking was a relay that was applying vacuum to the brake master cylinder when the car 1st starts up and that this was normal. Does anyone else experience this relay clicking noise ? It's not just 1 or 2 clicks but it does it about 15-20 clicks before it settles down ? It's quite an annoying sound and I find it hard to believe that this is normal.