come to think of it, why exactly are they hiding it? Policies against dating in the workplace are to mitigate the issues that happen when people start and stop dating, basically all the attention and drama that goes into it at the beginning and the end. It's the same reason you're advised not to start dating in college. None of this applies to a couple that's already at the point of being legally married.
Further, if they just say their married, the fuck is the company going to do if they don't catch them doing anything?