Yes, and the main reason in our experience is earpad wear and tear.
Worn earpads tend to affect the frequency response of your headphones. Depending on the model, the change in response can reach 2-3 dB in certain frequency bands.
If your earpads show signs of wear (e.g. they are deformed and flat), we recommend replacing them with new ones before mailing the headphones to us for individual calibration. Because your headphones will be calibrated with brand new earpads on them, you will always be able to return to the original calibrated sound by replacing the earpads.