What the other guys just said is exactly right. You did well my man. Legs cramp up on some days... could be a million things. I'm only 36 and my legs cramp on just about every run. The chances of something going wrong over 26 miles is great. You handled it well and still produced a great time for your age.
You rush back and run another competitive marathon too soon, you will likely do worse. Your legs will suffer. Take 2 weeks to recover, then start back with 25-30m/wk and work your way back up in mileage. The very earliest I would do another marathon would be mid-January.
My second marathon I ran 3:08 at Big Sur Marathon and I wasn't content with the time as I just missed Boston Qualifying. I rushed back and my times suffered because I never really fully healed.
Running long distance takes discipline. Sometimes discipline involves running when you don't want to and sometimes it even involves not running when you do want to.
After a long and fruitful 24-week marathon cycle, I go to NYC and come back disappointed. My performance was not horrible, but two very knowledgeable people thought I would go sub-3:00 (one such person is my coach). The last 6-8 weeks of my training cycle were especially good. I banged out tons of marathon pace miles, and many sub-MP miles, most of which with relative ease. I did 22 miles at an overall 6:53 pace (with plenty left at the end), and yet I averaged only 7:03 pace at NYC. I train in a hilly area, too. I peaked at 77 mpw.
I am 47 years old and my PR is 3:02--which was last year in my first marathon. I qualified for NYC 2016, and so I ran it. I felt great through the first 20 miles, truly thinking I had a sub-3:00 in the bag. I was 1:28:37 through 13.1, and cruising along First Ave., smiling and feeling very much in control. I get to the Bronx, and start feeling pain in my quads. The pain got worse with each of the final miles, and then my hamstrings, at about mile 23, joined in the pain party. What is really strange about this is that I NEVER get muscle pain during a race--never. I was shocked when it started happening. I got a slight twinge at about mile 23 at Richmond last year, but I slowed about 10-15 per mile, and felt okay at the end. In New York, I felt awful in the last five miles, seeing my first 8-minute splits in ages (over the last 3 or 4 miles). I ended up running 3:04. No sub-3:00 and no PR, either.
I have a good friend who is a very knowledgeable and accomplished runner (25 marathons), and she thinks I should try a back-to-back, as long as it is two weeks away (not one week). I can still get in a race not far from here on Nov. 20. She thinks most of my problem stemmed from being away from home, standing line for hours, and having different nutrition. I gather I had cramps? The pain was pretty bad. Again, I have no experience with this type of pain.
What do you think?