What would cause the grill knobs to get hot when they before?

- Burner control valve assembly problem: There should never be direct heat hitting a knob. There is either the burner tube itself hitting it or the burner venturis have come disconnected/broken, allowing the flame to go upward toward the face.

- Knob problem: Knobs have internal components including a plastic body (which can melt), steel inserts, brass parts which may fail by melting or cracking causing flame to engulf the exterior of the knob. Over time heat and chemical cleaners break plastic parts down causing them to fail.