Depends on the led intensity. Like Hugo said, tape ( like electrical black tape ) or a piece of cardboard over the light should be enough to stop it from being recognized by the plant.
I've even read about plants that did not re-veg even under pole lights ( outside at night ), but not worth it to try your luck over those things. You're onto the right mindset, good luck mate.
My A/C has a real bright blue display and I used a piece of boxboard and tape to cover it. Green light is supposed to be safe for pot in the dark cycle but I cover those displays up too. I doubt your plants would notice one night of light from an a/c display.