After coming down to the messengers, Peter said: I am he. This recalls the words of the Lord, spoken by Him to the soldiers who came to seize Him in the garden of Gethsemane.
Of course, here everything differed in spirit, yet in form it had something similar. Therefore a likeness appears here also in the speech.
By asking the messengers about the matter for which they had come, Peter shows that it had not been revealed to him why he had to go. Only the command to go had been given.
And so, ready at once to fulfill the will of God if the course of events required it, he asks them decisively: for what matter have you come?
They answer, but not so briefly. They do not know that this matter is not momentary, since they had been entrusted to tell everything about it in detail.
Thus Peter could judge what kind of matter it was, and what should be done for its further grace-filled direction.