My 2002 ford escape with recent oil change at sears blew white smoke briefly then stopped. This never happened before or since. Did sears screw up?

You don't need additives. Modern motor oil, be it conventional or synthetic has all the additives it needs. Check the oil to make sure it's not over-full. Otherwise, they may have spilled some on the exhaust and it burned off. Running fine now, not blowing smoke and no Check Engine light, I wouldn't worry about it.

Thanks for the input