Without any explanation and communication as to why you are private and secretive, it's not wrong but I can see it causing problems. Turn the tables and ask yourself if out of the blue he always shut off the tv or computer when YOU walked in? Would you at least be a little curious as to what it was that he didn't wnat to share?

No in and of itself it's not necessarily a bad thing to have your own private time/space.. But I will say that you should be communicating to him about your needs in this area and help him to understand why you need that privacy. That way you can continue having your own space where you need it and he can more easily respect it and understand.