Sounds like just a one off, I've got five GKs and have never had a single problem with them. The oldest two are probably only about 6 months old, but they get used every alternate wash cycle and are still in perfect condition, better than any other nappies I own.

GKs have a 90 day warranty on elastic and stitching, so you should be OK to get it replaced if you've only had it a couple of months.