Key Data Point - HR During Marathon Pace Runs

I'm tracking one key data point for this training plan: HR on days when I run marathon pace.

Here is what things look like so far:
1/4/14 - 6 miles @ 7 min pace, 157 average HR
1/11/14 - 6 miles @ 7 min pace, 162 average HR
1/25/14 - 7 miles @ 7 min pace, 154 average HR

Thoughts:
- For the 1/11/14 workout,I remember feeling fatigued and stressed.
- For the 1/25/14 workout (today), felt great. Rested, fueled well the day before with eggs, rice noodles (pad thai), shrimp.

So far . . . so good. The last data point is encouraging.