FLAT TIRE.
This is the first one since changing tires in April. Considering I was averaging more than 1 per month prior - I should feel pretty good.
It was still dark, I'm about 4 miles into the commute, going full blast (top gear, in a free spin) down a huge, steep hill when I felt a little wiggle in the rear. I looked down, looks OK, another wiggle.. oh snap it's going flat. I rolled to a stop, pushed to a bus stop - rode the bus on in to the office. I haven't even looked at the tire yet.

Once I get the morning routine going I'll pull the tire and see if it can be repaired here at work.