are you looking at the blotch on the lower left of the yellow? if so, it is not just the yellow, the line continues through the blue too... looks like some kind of contamination, either working through from something on the surface, or something that was spilled and wiped on the outside. (though I am leaning toward a trace of a volatile chemical on the surface before application - from the pic. there is not really enough data to be certain.... any more pics? how was the surface prepped before the install?)