are you leaves getting crispy or anything other than yellowing? when plants go into flowering they focus more on growing the bud using more K than N. bloom nutes often dont have N or its very minimal, thats why your seeing yellowing. some nute schedules call for N in the mid-flowering just to bring it back up just a tad, which you really dont need but couldnt hurt. my plants get like that but my nutes have me add a lil N in the mid flower. but to sum it up and answer your question, yes when flowering your fan leaves will get like that, you plants main concern now is budding rather than vegging.