What day cycle were they on indoors? What is your day length now? If they were on an 15-24 hour day inside, they'll probably begin flowering. I keep my girls on a 14 hour day in the spring to keep, or return them to vegging. I wouldn't worry about it. You'll get a 'stretch' that will double your plant size, and they'll finish about the same time, anyway. Remember the 14 hour indoor 'day'.