'15 Impreza Front Diff Leak

Hey y'all, I just got my oil changed on my 2015 Impreza and the mechanic pointed out that my front differential seal is leaking. They quoted me $1300 to replace the seal since they apparently have to drop the entire transmission to get to it. They did take me under the car & point out the leak & how they would get to the diff, but $1300 is a decent chunk of change and I haven't been able to find much online about this issue. Are they trying to overcharge me?