First, congratulations for coming out to your friend and sharing that part of yourself. I can understand your frustration with what happened. I remember when I first told my best friend at the time, he acted a bit odd and avoided me for a week, but then everything was back to normal--he just needed to process.

Here's the thing to remember, no one is a mind-reader. You're not exactly sure what he was thinking and he isn't sure what's in your mind. I would suggest talking to your friend. Give him the benefit of the doubt and allow him to explain it. You can share with him that you realize this might seem a small thing to him, but to you, it's something that's on your mind because sharing your bisexuality is a new thing. Always talk it out. What you're currently doing is a bit passive-aggressive and it's not fair to either of you.

Sometimes, we need to be vulnerable to share with people. Your conversation could go: hey, I'm not sure if you intended this but when you sat in the other seat, which was different than what we normally do, I felt like you were trying to distance yourself from me. What was going on with you at the time, I would love some clarity because I'm a little confused. I don't want anything to change between us because of what I revealed. What can I do to you feel more comfortable about all of this?

So consider being the same type of friend you want your friend to be: one who communicates before changing their behavior and negatively impacting the relationship.