I'm not sure why no one has replied yet...
I'm also no expert, but I have seen reccomendations to boil up some water and add light/dark dry malt extract (depending on your recipe) and add that to the beer. Of course you want to make your addition overly malty to compensate the rest of the beer.
Mostly though, people will tell you that your beer will be fine, and don't sweat the small stuff. If the gravity reading was 'close' to the expected gravity, then sometimes it's not worth risking infection to bring it up.
Also, people will ask for your recipe, yeast, and gravity readings.
Good Luck!
