Hi Vlaude and welcome to the forum. Since sand is the most popular color, it stands to reason that it has the most defects. I don't think color has anything to do with leaks; leaks and other defects are relatively rare but since nobody squaks unless they have a problem, they sound more prevalent than they really are.
The boat warranty goes with the boat, not the owner; so being a second or subsequent owner isn't a problem as long as it's a warranty issue. Hobie is excellent about replacing defective hulls, so if it's under warranty and actually has a defect, you might get a new hull for the price of a used one!
There is one "fix" that is available for your model -- new longer screws for your drive cams and reinforcement for the drive well. It's free from Hobie and it comes with instructions. See the nearest Hobie dealer for details.