Cartier Serial Number Question

[king0fhearts]

I just purchased my first Cartier (santos medium) and noticed the full serial number on the card is not engraved on the watch case. The card has 10 numeric digits + 2 letters while the watch only has 6 numeric digits + 2 letters; the first four numbers on the warranty card is not on the watch.

I bought it from an AD so I’m not doubting its authenticity however, this is the first watch I have seen where the full serial number is not on the watch itself.

Is this normal for Cartier?

Thanks,