And you haven't changed your saddle or position lately? How about have you lost weight or lost dimension (firmed up or lost weight)?

Depending upon the short and how many times you've washed them, I have noticed that the seams is where I see the wear on my shorts. Usually due to a break down in the lycra so that the short doesn't fit as snug as it once did and you get friction at the seams.

My current batch of shorts has an average age of about 1.5 years and I'm starting to see problems. However, they weren't a very heavy lycra to start with and I wash in hot water so I expect a shorter life span.