Advice: First corporate job, not sure if this is weird

F, 25. Just went to an after work event at a bar. It's my second week of work and networking is a huge part of our job (I'm a lawyer--networking determines what practice group you end up in). A lot of people were drunk, but I just started so I was keeping it pretty sober. I was talking to a 5th year male associate about antitrust law (an incredibly unsexy topic- for the record) and a married female senior associate who I had noticed was staring walked over and came in between us and said something to him along the lines of "why are you flirting with the first years?!". She then grabbed his arm and dragged him away from the bar. For the rest of the night she continued to give me dirty looks while whispering in the ears of other people I worked with. This really took me aback because in no way did I find the conversation to be flirtatious at all, nor was I attracted to my make coworker. This is my first real world job since I went to law school straight out of college--Is there an unspoken corporate code that if youre a single girl that you shouldnt speak to single men in the workplace? Ive never previously thought about how it could be perceived. Ive been replaying the entire night on repeat in my head to try to analyze how any of it could have been perceived as flirting and the only thing I can think of was that both of us were leaning in to speak because the music was really loud. Was her behavior out of pocket, or am I the one breaking unspoken social norms?