Coat grill rack with non-stick cooking spray. Preheat grill on MEDIUM heat.
For the sauce, in a small bowl combine mayonnaise, ketchup, relish, 1 teaspoon of the mustard (reserve the rest), and chipotle powder. Refrigerate while preparing burgers.
In a medium bowl combine ground beef, remaining 3 teaspoons mustard, Worcestershire, and salt and pepper to taste; mix well. Form into 4 patties about 1/2- to 3/4-inch thick.
Grill, covered, 4 to 5 minutes per side or to desired doneness. During the last 2 minutes of grilling, top each patty with 1 cheese slice; grill until melted. Remove from grill.
Place buns, cut side down, on grill. Grill until lightly toasted.
Spread sauce on cut sides of buns. Place burgers in buns, top with lettuce and tomato, and serve.