Weird family incident- help

So last year me and my dad, stepmom, and brother went on this trip to New Jersey to stay at my aunt uncle and cousins summer house for a week. For context, my cousin was 12, my brother was also 12, and I was 16. My brother, cousin, and I shared a room that had 2 bunk beds. One day, my cousin asked me if I wanted to go upstairs to watch a show. I said sure and invited my brother along. My brother said no thanks. So my cousin and I went upstairs and watched the show. He picked this show called Cobra Kai which is basically a kids show but can be enjoyed by teenagers too. While we were watching, my aunt comes in the room, asks my cousin a question about towels, and then leaves. But I could tell by the look on her face that something was wrong and she didn’t want to say it. There’s no incident while we’re watching, then we just go downstairs when the show is done. Fast forward to when I arrive home, my brother says in a mocking tone “do you think the way you’re sitting with (my name) is appropriate?” And he was clearly reffering to something he thought I knew about to make fun of it but I hadn’t heard anything about this. Then he explained that he has walked into the room one day and found our cousin seemingly pissed off so he asked what was up, and apparently my aunt had implied that the way my cousin was sitting with me is inappropriate. He even called up my cousin to prove it. My cousin was kind of squishing me into the wall, but otherwise we were just sitting normally watching the show on a laptop. I wasn’t uncomfortable in any way. Well now we’re going to go on the same trip again this year and I don’t want a repeat incident cause that was so embarrassing but I also don’t want to push my cousin away. I’m also worried it’s going to be awkward in general. Advice?