I suspect that it is an oil. The lures are dry to the touch, and even drilling holes the lures still appear dry. However, I noticed they were sweating after releasing from the mold for a couple days. But once again, they seemed dry after. I even put mine in the dishwasher to try and clean the surface (which worked well in the past). After this, these lures were probably bare for almost a month before priming.
My recent batch I dipped in kilz white primer (as suggest by other TU folks). After a day of hang drying in the garage, I moved them outside into the sun to try and ensure the lures were dry. Upon doing this, every lure started to blister and sweat causing the primer to become soft and sticky. It has been 2 weeks since this happened and the primer and lure surface is still wet, so I presume this must be an oil.
If I'm lucky, I'll be acquiring a laboratory oven, with lo-temp controls. I think you are right anglinarcher, I'm thinking lo-heat (probably about 100-110F) for several hours to see if it pushes the "sweat" material out. Step one is to remove the bad primer though, which will not be fun. Then, I'll try painting one again after trying the drying process.
If it is oil coming out, then why? My pours have been coming out great, just emitting this oil. Perhaps moisture contamination must be causing a chemical response. A call to the manufacturer may be the best way to go for answers.