I prayed behind a Pakistani imam who said the closing salam only once. Is the prayer valid?

The questioner:
Well, Shaykh, a week ago, Shaykh, I prayed behind a Pakistani man in congregation. When he finished, he said the salam only once, then prostrated for forgetfulness, and then said the salam. I was confused, Shaykh, about this matter. It appears he forgot before I arrived, because I only caught up for the last unit of prayer. So he said the salam only once and prostrated for forgetfulness.

The Shaykh:
He stands, he stands, let's give him.

The questioner:
You see, it comes.

The Shaykh:
More than.

The questioner:
I mean, is this correct, Shaykh?

The Shaykh:
You said the salam, so the correct thing is that you said the salam.

The questioner:
Well, do I have to repeat the prayer or what, Shaykh? Or not?

The Shaykh:
You said the salam.

The questioner:
I said the salam with him, Shaykh. I said it twice.

The Shaykh:
Praise be to Allah.

The questioner:
There is nothing to it.

The Shaykh:
Well, no problem.

The presenter:
May Allah preserve you. May Allah reward you with good, Shaykh. Peace be upon you. This question was taken from the poet Zambaz on the evening of Tuesday, the twenty-first of Dhul-Qa'dah, in the year 1416 AH.