Interesting. What's next? NOT telling a pt if you messed something up, esp. if they would not find out about it? Tsk tsk...ethics are a slippery slope. Once you start sliding, it is difficult to stop.
Individuals are offered a spot under a certain premise. What would look worse? The school finding out from the person who made a mistake, or the school finding out from another source. In the first scenario, if I were a Dean, I would listen, be upset, listen some more, commiserate, listen even more, advise, and thank the person for having the balls to come forward. Ultimately, he would be forgiven and his spot retained. In the second scenario I would tell the student, "why am I finding out about this from x? Are you kidding me? I am sorry, we are pulling our offer. We value integrity and honesty in our program, and now feel you are not a good fit for the school. I have several hundred candidates with similar numbers who I feel would have handled this situation appropriately. Good luck next cycle."
I am not on an ethical high horse. I have had nearly 13 years of professional experience where ethics are a driving principle. I have made plenty of mistakes. Ones which were discovered by sources other than me were painful experiences, and those were I turned myself in were respected and appreciated.
Don't play the game of waiting for the law to decide your fate and thinking this will swept under the rug. Be accountable for your own actions. At the end of the day, you will be able to rest easy knowing your instincts and morals were not compromised. Mistakes are the greatest learning tool ever devised. It is far easier to learn from times when you messed up than when you succeeded.