Welcome to the world of Heavy Duty trucks. To answer you question......Yes, this is common with Dodge and Ford also. This has been an ongoing topic here on the forum for awhile now. A lot of people are seeing the "V" on the back of their hitch and thinking that they have a Class 5 hitch. Not the case. The Class III hitches that I sell to the public actually have the "V" on the back of them also. So it's not something the auto manufacturers are doing. If you're going to exceed the tow rating of your hitch purchase a Class 5 hitch.
Some people here have had luck with the dealer stepping up and taking care of them in this situation. You might try this.
PS. Please upgrade to Class 5 ball mount and ball too. A Class 5 hitch will do no good without these!