Weird Encounter with a Straight Friend (HELP!)

So, I went to the movies with the one straight guy who knows I'm gay. Thus far, he's been really cool about it - he's known for about two weeks now. We aren't super close, but we are good friends. He has a crush on my sister, and he's been trying to get with her and I've been mediating that stuff for him. So (not that he's a bum normally) but normally he doesn't try really hard with his appearance. Well, I go to pick him up, and - dude cleans up nice. He did his hair, and was wearing nice clothes...nothing fancy, just nice jeans and a hoodie. He kept making comments about whether or not people would notice (specifically my sister) that he cleaned himself up. He looked good. And he was wearing cologne and crap.

His room mate told him he looked like he was going on a date, and he was like "No, this is just a chill night to hang out" (there were like 6 or 7 in our group). He tried to talk to my sister, and she completely shut him down. He didn't seem too upset about it, and he and I talked the whole 30 minute car ride.

At the theater, we sat in the back, a couple of rows from everyone. Laughed and talked and ate popcorn until the movie started (we had the theater pretty much to ourselves). My sister ignored him the whole time. Wasn't trying to make it weird at all, but it's exactly how I would want my first date to be. Super low-key. Just us having a good time together.

I didn't think I was super clingy or weird or anything - we talked all the way home, and when I dropped him off at his apartment, he was "We'll have to do this again sometime" (meaning with the group).

I don't know, maybe I'm making something out of nothing. It's probably just my social anxiety talking.

I wouldn't have said I had a crush on him before, but I definitely have similar feelings from my last crush. I don't want to make things weird between us - do you think I screwed up? I know I'm not the first or last person to have feelings for a straight guy.