Bettyboy72 said: "Bernadette is a true Broadway baby, She typically stage doors and is nice. However, with the bitter cold and flu season she might be playing it safe until the weather gets warmer."
I've heard that that's the reason several times, and honestly it makes a lot of sense. At any age, the flu can knock you out of commission for days, if not a week or more, and the risk only goes up with age. Given Bernadette Peters' previous love of the stage door and meeting fans, I would be very surprised if she doesn't start to at least occasionally come out once the peak of flu season is over.
Can't say for Victor Garber, but like another poster I got the sense he wasn't a huge fan of the process even without the cold/flu risk.