It's a way for the plan to say it is too hot for the humidity. You don't need to lower your temp you can up your humidity.. Handy dandy little chart I like to share to explain it a lot better then I can. If you look at vegetative growth under 25c you will see you are in the red at your current humidity... Get a humidifier you'll thank yourself in the long run and so will your plant.
http://www.just4growers.com/media/23631/vpd_2degree.gif