That's what mine have done (mostly something I ran into re-integrating broody hens who were starting up laying again). Yours may have either skipped a day or hidden an egg somewhere interesting. Some chickens will also eat eggs laid in weird places eve n if they don't peck at the ones in nests, so it's possible for there to be no evidence. I had a hen lay an egg off the side of my lap once because she wanted hugs more than to go to the nest box, and that stray egg was devoured in minutes, shell and all; if I hadn't seen it I'd never have known.