Sounds like me, Jim. About once a year I remove the grate and scrape out the inside with a plastic putty knife. The grate gets pressure washed. In between annual cleanings, it just gets burned off prior to or following each use.
2015 F150 2.7 EcoBoost (Big Spot)
2015 5.0TA (Little Elsie)
"What a long, strange trip it's been....."