If you bought it new I'd suggest a warranty visit to the dealer.
Failing that, some pics would help. I'd guess a screw is missing that should hold it in place or perhaps some caulk.
Good luck and welcome to JOF.
2013 F-350 CC SB 2WD 6.7PS
2013 Eagle Premier 351 RLTS
-SOLD- 2012 X23B
-SOLD- 2003 Ford Expedition 5.4, Bilstein shocks