One reason a solvent based lacquer can "milk up" after spraying has to do with the Dew Point. As the faster drying solvents in the lacquer evaporate, they lower the temperature of the substrate they left behind. If they lower it enough to hit the relative Dew Point it will cause moisture to condensate on the cooler surface. The moisture becomes entrapped in the lacquer and due to incompatibility you get milkiness.
In hind site warming the can may have actually exacerbated the problem. The warmer the lacquer is the faster it drys the quicker it will draw moisture out of the air. It may be better to actually warm the bait/piece your coating instead of the can to keep the lacquer film from getting to cool to quick. Just a theory.
The manufacturer should have some guidelines or perhaps a Tech Data Sheet they can provide to give some pointers to prevent this issue. It might be worth firing off an e-mail or making a phone call to the Tech Support and see what they say; if they have one.