Maybe she couldn't "give in" because she was on probation and as such unable to show any discretion, as opposed to having an "I'm a copper" attitude? Don't let one incident tarnish your opinion of a very overworked, and underappreciated profession.

I'm applying to join the special contabulary with a view to becoming a traffic copper one day, and after talking to several regular coppers about various aspects of the job, it's those kinds of attitude that MAKES an officer want to find something to arrest you for. If you get the arse with a copper, they'll assume it's probably because you have something to hide, hence the questioning! If you've done nothing wrong, you literally have NOTHING to get excited about!

I appreciate your reason for having your hand near your ear, but with 99 out of 100 people they encounter are actually on the phone, is it any wonder they wanted to see what you were doing?