I would wait until your next oil change & either mention it or if your dealer has a reason for visit form, write it down on the sheet & mention it
Ask the Service Writer to see what they can do for you, they may need to consult the Service Department Manager & that person may have to check with the people at RAM.
If you are told right off the bat, that because it is plastic, it is going to cost you $ X, contact RAM directly, preferably by Snail mail & politely explain to them along with pictures & ask them for their advice.
Always be civil & try to even smile when trying to work out warranty issues, believe me, it goes a long way. A pleasant customer sometimes gets things done that are truly outside of the print on the warranty, there is GREY area & sometimes they are willing to enter it when someone is acting like a friend
Ramtrucks Contact info
By the way, if you contact them at Customer Assistance, you can ask for a BUILD SHEET, you will need your Mileage & VIN # when you ask for it, it has nothing to do with the warranty, but i am sure glad that i have it. It is a 3 page listing of everything about your Particular Ram. It is a great reference tool & it is FREE