My gf gave me her phone to charge it because the bad weather caused some problems, whatever.

She has a colleague whom she understands well and at a moment i say he was calling her and on the screen was appearing a photo took at school with them. I didn't answer, i didn't want to appear jealous. He has a girlfriend too.

Tonight i'm meeting with her and i don't know what to do. I know that it isn't good to appear insecure but i feel i have to do something because is annoying. What should i do/say to her, guys?