That ties in with some arithmetic doodling I've been doing.I had a coil reading about 4 ohms. I took it apart and the top coil was broken in two. I remember checking the 2 coils to see if they were the same length but don't remember the results.If the coils are equal then the only explanation for a reading more than 3 ohms on one coil would be the heat burning the wire thinner because of the extra power applied after the one coil broke or burned in two. The Kanthal could change resistance with just applying the higher heat but I don't think it would change a full ohm. IIRC the coil that I mentioned also read around 4 ohms cool.
IF the istick 30 frequently reads about 0.1 ohm high, and the 2.5 reading I got very suddenly indicates that one of the coils failed, then by the forumla you gave earlier, the remaining working coil was 2.4 (or thereabouts) and the dead coil had been ~3.95 to 4.0 ohms. So much for building to spec.