Questions

My boyfriend is currently overseas visiting his old housemates. He went with a friend. His first week there he and his mate travelled in one of the main cities before going to the city their friends now live in. Second week of the trip they went to the city there friends live. There is currently a festival going on there that has the name of the city in the title. My boyfriend was going to this festival. 3 days into being in his friends city he makes an insta post of them going on a hike. As I was commenting I noticed another girl commented. She said "aren't you adventurous". My boyfriend and I both have friends of the other gender and usually I wouldn't think twice about this. However, I had never heard him mention this particular girl before so I became curious and checked her profile. She had posted a photo of her 3 days prior going to this same festival and he had liked it. I'm assuming she works at the local bar they had been going to as she already followed his friends that live in this city. I guess he met her there and they started following each other on insta. Something I found weird though was that she didn't start following the other friend that is travelling with my boyfriend. She hadn't posted for months before this. Is this weird? Was her comment flirty? Is it normal to comment something like that on a guys post when you've only known him 3 days? Should I be worried?