I'm on a watchlist...

[Ade]

I mean literally, threw my passport at me and said ‘you can go’.

Hate it when such things happen. I'd have expected (barring spilling of anything that shall not be mentioned) at least a courteous and emphatic chat on why they had to retain you, what was done to verify the identity and say that nothing to worry with an all clear.

Something along the lines of a calm explanation such as "we understand this is frustrating, but we are sure you will appreciate we need to do everything we can do make everyone feel safe. This is not a reflection on you, just a routine check conducted as a consequence of an alert popping in our systems. Due to security reasons, we are unable to disclose what the alert was in regards to, however, please be rest assured that everything checked out in your favour and you are free to go. Thank you for your patience in this matter."

I also ACK that this is not going to happen - but it would have been nice, I'd think. #WishfulThinking