Yes, its a clear plastic filter. I normally use a metal one (which also emptied after a day or two), but switched to this plastic one so I could see if anything was collecting in the filter (its clean). When the engine is running, the filter is about 1/3 full, which I think is normal.

Is there a check valve or a seal in the stock fuel pump that's supposed to stop gas from draining back? Other cars I've owned always had some fuel in the filter, though the filters were located further away from the engine in a more "level" location and those cars had electric fuel pumps.