That's a tough question, and it's happened before to me. It definitely makes things a bit weird for me.

If I have a prior relationship with that person, then to some extent they've already seen "full tombert" so I don't have to worry as much, but I'd be lying if I said that there wasn't a part of me that worries a little even still.

Quite often it turns out that the connecting glue that held the friendship together was the shared experience of the same job. Remove that and the friendship fades away.