I've never used an offset smoker, so only speculation or guesses from here. Was it a windy day outside, can wind stir things up inside an offset? And did you let the briquettes get to temp before putting on the chicken.......I know I've had some chicken come out tasting like petroleum if you don't get the briquettes going right at the beginning. And I know chicken absorbs smoke(as well as other flavors) like a sponge......to much smoke can be overbearing on chicken. There may or may not be an answer in here, lol, but just guessin' here anyway.
Weber Performer with rotisserie ring, 22.5OTS, Maverick 732, Weber Smokey Joe,PBC Smokenator/Hoovergrill, variety of microbrews, Gin and tonic, variety of lighters.