The main difference is hop utilization. By adding it at 60 minutes, you had a higher boil gravity, which means lower hop utilization, which means a slightly less bitter beer (not that it's a bitter style to begin with). Once the mistake was made, you could have boiled for longer than 60 minutes to offset this.
Also, the beer can be darker with a long boil. That's usually an issue with pale beers.
All told, this wasn't a big mistake.