This is not a problem with "non-compete" per se, but with use of confidential/proprietary information such as who's employed, what's the org chart. You have a much better case if the ex-colleague publicly shares his contact information, say on Facebook or Twitter or LinkedIn. Otherwise, your ex-boss could make the argument that you "stole" or misappropriate company confidential information. Yes it could be a very weak case but I have seen such threats being made. The etiquette is to not actively seek ex-coworkers for say at least one year. On the other hand, if you drop hints and the ex-coworker initiated the conversation about joining you, then you're fine. That's my take (not a lawyer).
Like the other commenter said, you did a dis-service to yourself by notifying your ex-boss, especially given your wording (face-palm).
Like the other commenter said, you did a dis-service to yourself by notifying your ex-boss, especially given your wording (face-palm).