Simple credit card fraud flag. Occurred to my wife when she charged last-minute work trip to her personal (Chase Sapphire) card. Other last minute to corp charge card never had an issue.
What is unusual - as you know - is that you were CHARGED the amount, then they flagged it and had to present card (aka Card Present transaction) at the airport.

p.s. - what card did you use (V/MC/DS/AX)? and where were you flying to internationally? NL - or EU in general - hasn't been an issue. But as soon as you look to Africa, India, Brazil, etc. - it can get flagged.