We should look into our contracts and check if they disclosed that prices can go up without prior notice. This will help us determine if we will have to expect a notification or not. Some states have a law that advance notifications should be sent though, but not all of course. So digging up for that contract would really tell what to expect.
Considering the number of price increases Dish has had over the years, they should be experts at knowing exactly how and when to notify their customers of price changes. This is not their first rodeo.