Help! It's on the tip of my tongue.

[Exuberant Verbosity]

Please help me find the word / phrase that describes the situation when one has been pleasantly surprised by a situation about which they had a preconceived idea.

An example of such a situation appears in Afrika's poem Trespasser. The persona takes shelter in an abandoned cathedral on a rainy morning. He realises that he is not alone and becomes fearful and suspicious of the vagrants in the cathedral. Yet, a man approaches him and greets him with the dignified salutation of "Good morning, Sir."

Now, what do we call that? Please help. It's on the tip of my tongue and I just can't spit it out.