I'm going to presume that you are keeping a running log. Are you recording your pulse on waking each morning? If not, I recommend it as a reasonably reliable indicator of when you're not fully recovered from your last hard workout.
Also record your pulse one hour after finishing a hard workout. When those two pulse measurements are close to each other, you can reasonably expect to have a good race.
Just treat this 'race' as a time trial where you were not as fast as the last time, but where your legs were tired from training. If you can run that fast when tired, imagine how fast you'll be able to run when fresh!!! Your fitness has definitely improved, but this race was not what you were peaking for, was it? Focus on your peak races. Imagine the crowds cheering as you go by. Fly!