Earlier this year I was in Japan and Korea. Now I am back in my home country. However, when he was in Korea, the "scan" machine before moving on to baggage inspection, just before entering the boarding gates, emitted a strange "alert" sound. It has already happened at least twice, but both times the officer returned my passport and did not ask me anything. They just made sure it looked the same as in the photo.
When I was leaving Japan, before going to the boarding gates, when the officers scanned my passport, everyone looked confused but never looked at me or asked any questions.
I wonder if there is a problem with my passport and what could I do. I am a little worried even though they have never asked me anything every time this happens.