Maybe she was already stessed & bitchy before the 4 minutes even started?
Or maybe she had something important to do and was delayed by your tardiness?
Sure, its counter-productive to "behead" you...but when you arrived were you apologetic or non-chalant? Is this the first time you've been late or are you consistently pushing the time limit?
Is this really a sign of immaturity on her part or lack of respect for her time on yours?