Questioned while boarding DXB to LHR
 

Hopefully posting in the right selection! Traveled from KUL to LHR via DXB the other day with Emirates and while boarding I was instructed to go to back in the line to another gate agent who asked me what I was doing in Malaysia and wanted to see my Malaysian work visa. I'm a UK passport holder. This was before the extra baggage security area. It wasn't really a hassle but I'm more curious why someone might get flagged like I did. The only thing I can think of is that my flight was a last minute on the day booking. Thanks!