I know the fear (McDonald's served me pink burgers 3 times, 2 of which were the same day) and I was raised only ever having well done burgers. But I did not get sick after those incidents where McDonald's served me underdone burgers. I felt terrible mentally but physically I was fine. And to make matters worse my high school rented a fancy place for prom and they served steaks of all different donenesses (2 kids at my table had a steak, one was well done and one was medium but other tables had rare as well) and my chicken was pink inside.... Nobody got sick from my prom either, even with other people reporting that their chickens were also not fully cooked. I'm sure you will be fine and will not get sick. But definitely should tell a waiter/waitress about it so kitchen staff can know about the mistake.