I second what Tea said. You will recover your stamina rather quickly. And if you have to slow down just a touch to rebuild, well, the speed will return quickly too! Good idea to sign up for the 5K this weekend!
I have the same tendency -- to stop running after race. I did a half marathon on the 12th and have definitely cut back since then. I've done other stuff -- yoga, spinning, kickboxing -- but I know I need to get out there and run a little more...
Back in the saddle. Again.