I wore my crush's coat. Is that a good sign?

Well from personal experience I believe it means he is comfortable with you. Don't overthink it though. I wore my crushes hat once and he didn't seem to mind. As long as you didn't take it from him all should be good. Guys find it very annoying when you take their clothing and wear it without permission. Anyways I'm sure that doesn't apply to you since you said he didn't seem to mind. Maybe he likes you too, you never know. I suggest telling him since it seems like you know him well enough.