I think those 40 miles were over multiple outings in a week, but let's compare with a 26 mile marathon:

A very good but not world-level time for the marathon is 2:20 or so for 26 miles. That's more like 5:30 per mile. World record pace is an even more insane 4:41.5 a mile (http://www.runnersworld.com/newswire/dennis-kimettos-maratho...). So yes, 6:30 should be easy, if you're at that level (must be, given that I could do 10k in 40 minutes, which is around that pace, when I was a lot younger, and I'm not a running talent)

Right, exactly.

Yeap, this was my average speed over all my weekly mileage. My long run would range from 7:00 to 7:30 pace and would top out at 13 to 15 miles. My easiest runs were about 8:00 and my fast pace (probably 6 or less miles per week) was from 6:10 to 6:30. I would say I did seem to run my overall mileage faster than people that would destroy me in races (which is probably why I'm injured).

The 7:30 pace had my heart rate at 145 on flat ground in cool weather at age 40 for a 13 mile run which from what I understand is the right pace.