First Oly this weekend

So I did my first Oly which was also my first tri as a training race for a HIM in July.  All went well.  Did not tapper the week before and just treated it as my long ride/run for the week.  For the swim felt great.   I actually starting passing the wave in front of me even though I could not see a thing in green lake water(21 min).  Ride fine, just under 20 mph over the mostly flat course.  Run, took 2 miles to start feeling ok. Not so fast just under 9 min/mile.  Here is the kicker.  It was listed as a 10k run but they extended the run to 7.4 miles.  I thought I was on the longest 6+ mile run when I finally (and others around me) realized that we were headed for over 7 miles.  So is this common in tri's?  Given my "A" race is a HIM in a few weeks not a big deal but a bit hard on the spirits when you realize that you have another mile plus beyond what you thought.

While I finished this race upright and well within the time I set, I was tired and of course the back of the mind starting thinking that in 3 weeks I will be going twice as far and getting a bit nervous.  Normal?