That stall was twofold, Rich. One, to allow my son to get back into the car after taking photo's of me entering (you can see him off to the left as the gal tells me to hurry on) and two as you suggested, to allow me some fun time through the tunnel. Yeah that horn was a bit much, but it was so easy to get caught up in the excitement, especially for the locals who had been waiting for over 10 years for this project.
Here's another from the south portal with us at 5:02