That's not good! The oven/stovetop is supposed to be screwed into the sides of the opening. I'm guessing the LP connection kept it from coming out any further. Open up the top of the stove and then pull up on the front of the upper plate that surrounds the burners. Unhook that same piece from the tabs in the rear. Try to see if the original screws (on the sides of that burner well) have pulled through the holes or if there were any screws in the first place. Either way, relocate and level the unit as best you can and drive a few screws into the side frames of the rough opening. Two on each side, front and rear should do. Use washers to prevent the screws from pulling through again.