Are you sure they leaked and it was not just sweat from your feet? If they are truly leaking this has helped me to prevent leaks.

In my experience all neopremes will eventually start to leak. For me the leak is almost always at the feet. I have found what I think is a good foot saver for the neopremes. Go get the biggest pair of fleece socks you can find, after putting on your waders put on the fleece socks. This will help prevent anything that gets into your wading boots from rubbing directly on your waders. I used to blow through a pair of feet every 1-2 years. Since doing this I am on my second season with a pair of neopremes and have yet to see the slightest wear begin to start.