Can happen with any airline. Usually purchase involves last minute ticket or a ticket with a departure out of certain countries. Can also be certain banks they're having issue with, your country of residence, billing address country, etc..

If you bought online from delta.com it should've told you that this would be asked for.

As noted, if don't have that exact card anymore, they can swap it out. You should be charged same amount as originally, not a new last minute fare.

This will not occur if purchase via OTA. In that case the OTA is the one responsible if there is fraud with card.