|I have some diapers that I've used on two boys, and unless I pore over them, I can't tell the difference between those and the ones used for only one. Neither bunch has binding wear, just a little thinning here and there that it's really noticeable unless you're looking hard on the older ones. That seems to be more of the norm from comments on this forum, so I, too, am surprised that you'd be seeing this after gentle care and one child.
I'm guessing the answer is no, but did you use any additives besides the detergent? Is your hard water softened? Just curious, really.
Although I would suppose they're past a warranty period, I would still consider contacting ME, maybe e-mailing a photo of the wear to their customer service with a description of your wash routine. The information might be helpful to them, or maybe they can also help you figure out what could have caused the wear.