Standard temperature of ANY dimensional calibration is 20°C (68°F). Any variance from that temperature adds uncertainty, but does not invalidate the calibration. Your calipers, for instance, do not have the resolution to really show the variance due to temperature in any reasonable environment (example: ± 10°F, measuring at 6 inches, assuming you were using steel gauge blocks, would only bring uncertainty up about 80 µin, or 0.00008 in from doing them in a perfect environment).
But, having said that, I believe that what the DOD is looking for is for you to state your environment at the time of calibration on your certificate, regardless of what temperature it is. I worked at a DOD facility, and we did calipers at 73°F as a regular course of business, and it was well within the DOD required temperature range for doing so. You should have a specified range in your quality system that defines what temperature you have deemed adequate for performing calibrations.
Ryan