Unfortunately, it did get worse in a big way. The pain got sharper and sharper and around mile 5 on a downhill stretch the pain became so intense I thought my leg was about to buckle. I was shocked by the level of pain, like a knife was cutting me. Over the next few miles I continued to try and jog through the pain, but at some point it always became so intense that I was forced to walk. The amount of time I could jog between walk breaks steadily decreased until during the last mile I could not really sustain a jog at all. The worst were the downhills, when even walking was extremely painful and my leg threatened to give out completely several times.
It was so frustrating to have started off well, and to be still feeling physically strong but to be limited by that knee pain. In fact, when I finished the race I didn't feel tired at all. I was just in pain. My time was remarkably decent (a 13:30 average pace per mile) considering how much I walked during the second half. I'm glad I finished it, and I really hope this is not a nagging injury since my half marathon is only 2 weeks away.
In a lot of ways, this 9.3 mile run was the perfect warm up for my 13.1. I got to feel the same feelings of anticipation the night before, get up early and go through pre-race routines, deal with my nerves, and get off to a great start on the run. If the knee is healed up in time, I expect to do well on my half!