Are they all sticking or is it just one piston? And what bike is this on, Steve?
Never mind....ZX-9 eh?
Tell us about the ZX-9, Steve. We loves a good story, we does. Does it have two front calipers or just one? If two, are both seizing? If one, apply the brakes until it seizes and then open the affected caliper bleeder and if the fluid shoots out (put a rag over the bleeder just in case), then it's an issue with the line on back to the master. If not, it's caliper related.
By the way, is that the only thing you did (replace lines and bleed) or did you muck about with the calipers and did you change the banjo washers?