When you mentioned to him that you were once a Dub, if that was me I just would've left it there. Then let him think that maybe I was DFd, then he'd have to think "oh, no, just got a new job and I'm working with a DFd Dub, what should I do"? I bet if you didn't tell him you weren't DFd he would probably run to the elders and get counsel as to what he should do, which would be to ask. If he asked me I would've said it's not proper to discuss religion on the job and I don't have to answer that anyway, then let him run to the Elders again like a five year old runs to mommy.