Test labs are usually allowed to calibrate their own equipment to a certain degree, the equipment they use to calibrate with though, that's sent away to another company or someone comes in to calibrate on site.
As for being past calibration... it's never an ideal situation, but as long as you're able to prove that it was working as specified, for example, within spec next calibration, they you can probably get away with it. Just far easier for everyone involved if everything is calibrated.