Unless there is something in writing and signed by you stating you will not disclose salary information, then I wouldn't worry. I find it curious at the persistence of this individual to know how much you make.

Me, personally, mine is public record. *gulp* The issue with salaries as I, too, have grown up respecting the fact that such things just are not discussed, I find, is there is some level of expectation/pressure when such things begin to be analyzed and compared. It can lead to envy or job disatisfaction of others. On the other hand if living up to expectations it's a moot point. And many just go back to focusing on themselves.

Seems your coworker crossed a taboo line there. Maybe that fear of being reprimanded is better utilized by being miffed at their audacity? Misplaced anxiety?