Departure and arrival times are really a guide [}:)]
Though in reality, there are many things that determine whether a flight meets its scheduled departure or arrival time, think only about how may services need to be on time to equip the flight (crew, food, cleaning, fuel, etc.) and if one is late then that causes an effect. Also, the arriving flight might be late, or a passenger e.g. a connecting passenger, or probably hundreds of reasons. When in flight the headwinds might be stronger than usual, or turbulence causes a detour. On the ground there might be congestion and indeed in the air. In reality there are multiple reasons and 10 minutes or a 'little' more on a 7/8 hour flight really is neither here nor there.
That said, I have noticed a lot of work on the ground at DXB of late and my flights have generally been later than before. So that might explain it.
There's a plane at JFK, to fly you back from far away
all those dark and frantic transatlantic miles