Egads! OK, I rationalized the 164.0 on the scale the night before the marathon as water/glycogen put on in the last few days when I cut my mileage. I rationalized the 163.5 a few days later as water retention from muscle damage (inflammation). Now that I weigh in at 164.5 and can see it on my waistline, I have to accept that it's just fat. This might explain some of my "fitness" loss in the last month. Looking at the bright side, this means I have more room to improve.
Today was the 2 times the neighborhood loop. 9:40 min/mi, 133 bpm average. The breathing and heart rate were in sync finally (140 felt hard on the uphills). The pace dropped about 20 seconds/mile from yesterday, so thumbs up there -- only another 20-40 seconds to go. I felt a little more spring in my step. I think a lot of the post-marathon loss in pace must be due to inefficiency resulting from soreness/muscle damage. I like to assume that at least.