One of my cats gets that from time to time and it clears up by its own in a day. As long as there is no redness or discharge I would allow it a few days to clear on its own.
My kitty does that all the time. It just goes away. Did you examine the eye for a hair or something? I rinse her eyes with tepid tap water and a syringe to dislodge the hair or whatever is in there serving as an irritant.