They were praying for Peter as he was in prison and were surprised when they saw him. I think the second but most online resources seem to think the first
The Scripture says the Christians were praying for Peter not for Peter's release from jail. Their reaction to the sudden appearance of Peter is completely normal.
@suzie1960: if you don't want people "spreading" "Christian propaganda" on your posts wouldn't it be great if you didn't do the same idea to others'? In my own personal opinion there wasn't any need of you to say anything.