Mark you hit the nail on the head, I've done this before many times, especially when shooting the paint mixture with to much thinner, there is not enough pigment in the paint to cover thus leading to your results posted, the to thin mixture seems to pool and create this effect, I think it's on the verge of running but since it's on the top of the lure it has no where to run. Sorry I wish I had a better way to describe it, but it does make for a pretty cool effect. I've often thought I ruined the bait and wanted to wipe it off but went ahead and put the heat gun to it, sometimes the heat gun will make it seperate more, giving it a pourus, texted effect.
Please see example, sorry it's not the best because I tried to cover it with pearl mixed into the clear coat, but you should be able to see it well enough.
I should add, it happens to me mostly when I use Createx Candy Transparent Black, very rarely will it happen when using an opaque paint.