Graeme,
Wish I'd have thought of that with the broken bit of rod
Was a real pain drilling out that dowel without a vice or clamp, very nearly drilled my leg
I've blown that pic up as much as I can and cannot see any gaps in the thread but it is difficult to get a good idea without having the rod in front of me, maybe worth getting one of the more experienced guys to look at the build. I have not seen any other rods with similar thread therefore cannot make a comparison between your wraps and any others. It looks as if you may be wrapping rather tight around the guides as the thread looks a little stretched over the feet but not on the blank, this is something you would not notice if using solid colour thread which is all I have personally ever used. Can you move the guides at all once they are whipped on?
The other thing you could maybe do which might make life easier is grind or file the tops of the guide feet down a bit to reduce the height difference between the top of the foot and the blank, I didn't do this on the first rod I wrapped but have done it on all since. Makes wrapping easier and looks neater once finished. You could also try using solid colour thread, I think that would just make the unevenness go away!
Cheers
Ben