no. not a single problem. internet scares the shit out when it comes to cannabis growing. you can take photos of your plants every day with flash no problem. no revegging. it's not that easy,you should expose the plants to more hours of light just like veg,don't worry. the most that could happen would be to go hermie but I haven't seen a plant that went hermie because of my flashlight yet. for 12 weeks into flowering,noting to worry about. 2 weeks one is fine too.