i think you mean "gall", unless you're implying she had a seagull commit the crime. and yes, i consider this stealing. i will always leave some sort of tip, no matter what--for fear that this will happen. however, if i'm pissed with my service (and i eat out quite a bit, unfortunately), i make sure the manager is made aware before i leave. i will almost never accept free shit from the restaurant (unless my meal is completely ruined), which sends an even stronger message---some people bitch just to get free shit, and managers know this. if you gladly accept a free meal/etc., to the manager that means you're satisfied and will likely come back. if you accept nothing, the manager will definitely take stronger action with a shitty server. in this case, none of the above is relevant--what she did is stealing, any way you look at it. it is grounds for immediate dismissal. i'd go in and talk with the manager to give him/her the chance to 'make it right' before you go to the better business bureau, local media, or talk to your 'friend' who works for the department of health.
and man the fuck up and disclose what restaurant you were at--you're not going to affect the rotation of the god damned earth if you tell us where this happened.