boyfriend and best friend

Is this bad? My best friend had just started following my bf on Instagram and he asked me if I knew her (so he could let her follow him, nothing shady) an I said, "yeah she's one of my best mates from school" and he said like if a cough "she's fit" and then laughed and I was like "what" and then He was like "what." In a flirty way that we usually do and he was laughing at it. Is that normal? Should I have been more pissed or less pissed or is it nothing to worry bout