[MathReferee]

Certainly a combination of age and lack of familiarity. At least that was the case for me when I broke into V games. Proper play calling, proper mechanics, confidence, using voice, and good sharp whistles show them you're capable of handling the game. Beyond that, they will test you to see what they can get away with, so focus on professional communication, giving short, rules based answers to appropriate questions and then warning/whacking when necessary.