It could be a satellite radio antenna. On our 2005 MH, also made by Fleetwood, above the driver's windshield we have about a 12" - 14" antenna that's for the front AM/FM radio. There is also a small "box" looking antenna that's about 2" x 4" by 3/4" high that's for the satellite radio that came built into the front radio.
Bill
Nodwell RN110 out moose hunting. 4-53 Detroit, Clark 5 spd, 40" wide tracks, 10:00x20 tires, 16,000# capacity, 22,000# weight. You know the mud is getting deep when it's coming in the doors.