It depends on how old the oscilloscope is and how far out it is.
You can easilly test the calibration your self.
Measure a known DC voltage source with a new DVM and the scope and compare the two results. If the reading from the scope deviates noticeably from the reading by the DVM then it needs calibrating.
Measure a known stable frequency source, the mains is the easiest one, if it deviates significantly from the expected result then it needs calibrating.
I have two old scopes, both are significantly out of calibration but I don't worry about it because I don't use them for accurate measurements.