Well guys, i believe it's not a mistake in this context, but maybe native speakers could know better. Alesko's "last word in a last row" does contain a couple of mistakes though.
The phrase works both with and without the A in the last row. If the last word is a noun then the A is necessary. If the last word is a verb then the A is not necessary. By including the A the phrase relates to a particular instance, a particular matter requiring action. Without the A the phrase would be more general.