I agree. I've had two Dometic fridges and neither one has ever made a sound while either on propane or electric. I would call Dometic directly for added peace of mind. Here's the number: 1-800-544-4881. Here's their email:
CustomerSupportCenter@DometicUSA.com
The recall mentioned above started for 2-door units built from 1997 - 2003, then was expanded to include some units built through 2006 (I would be surprised if you had a fridge that old in a new rig, but you never know). However, here's that link for more information:
Official Dometic Recall - DometicUSA
Be very careful as these fridges, while used for years in RVs, trailers, etc., can also pose a fire risk when they have a component that is not working properly. Many of the posts on the 'net talk about Norcold fridges having issues, but the technology is essentially the same in a Norcold and Dometic fridge.
Be careful and be safe!