cedfire,

I've seen the same exact issue that you have. I bought a fresh pack of WetFire tinder after reading a promissing review on it. I place a few cubes in my PSK.

Well, on a camping weekend with the scouts, I was doing a bit of PWYP (Practice What You Preach). Well, I couldn't get the tinder to light with a spark to save my life... It did take to a lighter, but I wasn't impressed with the burn time. Seems that I had similar seam failures. This was true even for packs that were never placed in my kits.

Mike