If this is a big problem a visual check before you ride wouldn't hurt. Sometimes when stopped at a light on a group ride some friend will ride up next to you and tap the bifter two or three times just to be a joker. New riders panic and jump off the bike before the light changes and have to turn the crank to get into what ever gear the joker shifted them into. More seasoned riders simply look back at the cassette and see how many clicks it takes to get back in line.

Don't ask me how many times I jumped off the bike.