Is it normal for one eyelid to twitch for a day or two? why would this happen?

Maybe: Eyelid twitching is usually due to myokymia. It is usually not dangerous especially if it is intermittent and only lasts for a day or two. Persistent eyelid twitching can be more dangerous and should be evaluated. Myokymia can be related to many things most often stress, diet, and straining vision contribute.

Fasciculations: Yes benign eyelid myokymia or fasciculations could cause this due to stress, lack of sleep, caffeine, etc.