If it was just a few seconds of running, the roughness was probably just due to the water that was in the plug holes just dripping down into the cylinders. If everything is exactly as it was (as far as the installation being correct) I would bet that if you started it up and let it run, within 10-15 seconds it would be running smoothly again.
This happens to me at work sometimes. If there is oil in the spark plug tubes and I am doing a tuneup, I will clean out the tubes with carb cleaner with the plugs out and this liquid gets into the cylinders. It is hard starting at first but once its started give it some gas to blow everything out and it runs well again. (granted I also recommend replacing the VC gasket if there are oil in the tubes... lol)
I wouldn't worry about any kind of additive. You'll be just fine.