Blue and White on a cold engine is fuel, by itself or with antifreeze. Monitor the coolant level for any useage. Possibly could be air in the fuel system, if it only did it once and worked itself out. (Most likely) Air entry on the return side when it sits, like over night, can get back into the supply side where connected at the filter housing. (I don't like the return fed into the supply) It takes a little time, but the air gets sucked back through the pump, then can cause white smoke as it exits through the injectors. Since air is compressable, in the injector it screws up the spray and exits at low pressure, resulting in poor burn or no burn, which was your miss. Antifreeze puddling on the piston or in an inlet port can do it too, but not likely if performance was good later.
Check fuel lines for tightness or worn spots. Could be on the supply side too.
See if it does it again after it sits overnight.
One last comment. Sometimes you can get a miss if you overfuel and over load / over accererate cold, usually on the first or 2nd gear at the first start if at low rpm (1200 - 1500). I have heard this miss on many 1st gen with rotary pumps. In fact, I have seen them flame out entirely, until the driver got off the gas.
good Luck
Doug Rees