This is true. Sometimes Disney raises prices before they release free dining. If they do, you will need to pay the new price in order to get free dining. It shouldn't be a huge difference in price-- free dining will discount your package way more than the increase, but it is good to be aware of for planning purposes. The number you have in your head right now as your package minus the dining costs could be a bit more because of an increase in the overall package price before they release your free dining promo. Also, people say not to book yet for FD because it fills up the rooms, but if you are before your 180+10 date, and you want a hard to get dining reservation like Be Our Guest dinner or CRT before park opening, you need to go ahead and book so that you have the +10 advantage for booking dining. In almost all other situations, you can wait and just book dining daily at the 180 day mark, but for certain reservations, you really need that +10 advantage.