I don't think you need to worry about it; if you see one another in a future life, he'll know whatever rules there are; they're only important to his career, not to you, you can't be "unethical" wanting him :-) I kind of doubt, if he's a resident, that he's looking for a relationship though for a few years anyway and/or probably has one? I'd just forget him, chalk it up to attraction to a nice guy :-)