An entree served at a recent neighbor's cookout was skewers of marinated grilled chicken breast. They looked delicious, but the chicken pieces were gummy. Not chewy, not rubbery, but gummy - as if there was a soft coating of what FELT like disintegrated chicken on the outside. The chicken had not been previously frozen. It hadn't been marinated more than 4 hours, and the marinade was soy-based. The skewers were cooked on a gas grill at medium heat. None of us could figure out what could have caused the gumminess, and I've had no luck finding anything online to explain it. Any thoughts?