delta gooseneck faucet shuts off slow!

The delta faucet is about 8 years old and a gooseneck style faucet. It has no baseplate. spout in one hole,hand held sprayer in another and the water control and temp. adjustment both are controlled by a single handle. Possibly a 172 waterfall faucet in white.Number could be wrong, going from memory. Problem is the faucet shuts off slow even if you close the handle control quickly. while i'm only talking about a seconds worth of water wasted it is bothering the owner. I put a complete rebuild kit in it, so the only thing i didnt replace was the diverter. where is it on this faucet? I assume it has one? Is there something else i'm missing? the home owner says it just recently started this (I suggested the kit).

The diverter is in the front of the handle unit. The only way it can continue to flow when the handle is turned off is if there is residual pressure building up somewhere, possibly in the hose. Try operating the hose before turning it off, to see if there is an "air bubble" building up to create the pressure.