Could be a couple of things. I've had that happen when I've wrapped too loose, but you don't want to go too tight. It could also be that your wick wasn't oxidized enough and the wire is continuing to oxidize one part of the wick and when it gets moved it has to do the same thing on the next part of the wick (would change the ohms). But I'm still betting on too loose. I use 28 guage as well and springy or not its still thicker and a little bit harder to get a nice wrap.