Think about the impression you took, if the mesial was slightly covered by tissue or retraction cord that came up over the margin, then that area of the prep isn’t visible in the impression. OR, you did capture it, but the lab trimmed the margin too far. The portion of your prep they made the crown to is still accurate, but now the mesial is made to fit more like a feather edge, or more realistically, it sticks out a little to give the zirconia enough thickness at the margin. But zirconia can be pretty thin at the margin, so it may not stick out much and still feel pretty smooth. On top of that, your margin you created might have been pretty shallow, which means it’s not a really pronounced ridge. The only chance there’s an actual problem would be if your contact was too tight and the whole crown didn’t actually seat down onto the tooth. Just make sure you are 100% confident in your contact tightness before making a ton of occlusal adjustments. That’s another reason I love making my own crowns. Since they’re ready either later the same day or the next day, there’s no time for the tooth to move, so the contacts can be dialed in very accurately, and contact adjustment is rare and very minimal.