This sort of heavy price changes is the sort of thing that happens 10 months out. There is a technical reason for this relating to predictions of demand, and I would completely expect the price to fall again just as sharply at some point in the future. But your booking is safe at that price, and even if it was a booking on hold or on the 72 hour guarantee, BA would not seek an increased price. So that's the good news. The bad news is that those who book a long way out have a greater exposure to unexpected events that may change what is at the moment a very firm plan. So if it's a big expense you do need to consider that your travel insurance is in the right place with the right coverage to consider the unknown unknowns.