I like to think that they were for the moment staggered by the immediacy of the answer. Angel deliverances seem to find no place in our modern theology. Perhaps we would like the Lord to answer our prayers with the least embarrassment to us. But supernatural results came for many of the praying saints of apostolic days. The Lord geared a property-damaging earthquake to get deliverance for an apostle.
Prayer is dynamite.
There is no weapon formed against prayer that can neutralize it. Some things can delay answers to prayer, but nothing can stop the full purpose of God. The first requirement in prayer is to believe. Reflecting on the story of Peter, I am rebuked, humiliated, chagrined, stung. Because there are some great modern saints, Watchman Nee for one, who for years have suffered and been held captive by communists and others.