Note: Specialized issued a recall January 2019 for certain Future Shock headsets. Not all bikes from all model years are affected. Addressing the recall involves replacing the steerer tube collar to improve its resistance to stress corrosion cracking. All Future Shock bikes sold at The Pro’s Closet are inspected for this recall and serviced if needed.
https://www.theproscloset.com/blogs/...vs-trek-domane
...apparently these have gone through some redesigns over the various year models since they were introduced, and some of them were problematic. Not sure if yours was "replaced" with something updated in design, but I'd definitely check with the dealership about recall under warranty possibilities. A cracked collar on the steerer tube would definitely be a possible source of he sort of noise you describe.