I have a grohe kitchen faucet with pull out sprayer. Nice faucet, but it leaks (when its off), if we leave the handle anywhere towards the cold side, closer it is, worse the leak is. I.e. if I turn it off with the handle all the way over to hot, no puddle at the base. Leave it in the middle , medium leak, all the way to cold, big puddle. I first noticed some wet under the sink (cabinet), But nothing leaking from pipes/tubes/traps. Then I saw a drip come down from the hole in the granite that the faucet fits into. At first I thought my son was splashing water onto the base when he used it, but then it happened when he was gone for 2 weeks. I started rubber banding a paper towel around the base, and noticed it only got wet when the faucet was off, anywhere but the full hot position.

I read that this could happen from mineral buildup, (I do have hard water)..and I should clean the cartridge with vinegar and replace it. Any ideas?

It's been happening for over a year. Not annoying enough yet to make me run out and buy anything or call a plumber.It doesn't puddle up as you watch, but if I come back a few minutes later, I can see the puddle starting. If it stays towards cold all night,I have a dinner plate sized wet spot with corresponding wet spot on the puppy pad under the sink. Plan to sell house in a year, so I have to start fixing these little issues.
Thanks

The water should not drip down into the cabinet unless it's leaking at the hose to spray handle connection in the spout. That should be checked first, then the cartridge could be removed and cleaned if required.

contact grohe for free cartridge. their tech support is really good.