Once again, don't read too much into this. My advice would be to tell her, but I would not make the next call to her. Let her call you and when she inevitably asks, What's up," then you could let her know. It's also not necessary for you to answer a lot of questions about the new sitch, other than he will stay with you until he finds his own place and settles in.
As for the mystery, I'll presume that since this guy was your best man, you have a lot of joint war stories and you'll also be his guide and partner in finding the great lady places in Seattle. This is sure to catch W's attention, even if she acts as if she thinks it's great.
Btw, have you been in Seattle a long time? If so, do you remember a radio DJ Steve Rabow?
