It is done all the time, but the ball is spotted incorrectly more times than not, often by a foot or more. You watch any play and you will see errors on almost every spot. It is the most imprecise ruling in the game, but we must live with the human judgement. Calling the touchdown was not a bad call. It just may not have been the correct call, but it was within the margin of error of what you can expect from a human being.
It was the correct call.