Except that if you're already working for a tech company you have likely signed an NDA/Intellectual Property Assignment agreement when you started your job -- thus muddying the waters from a legal/IP point-of-view for any work you've done (even outside of your work hours).

* Except in CA as the state outlaws these kinds of shenanigans, and rightly so!

Just keep your mouth shut about what you do in your own time and you'll be find.