Communication is key.
If you're going to take this friendship - romance seriously, its imperative you two learn how to talk to each other.

Before we started dating, my boyfriend was one of my best and closest friends.
But suddenly I discovered I was very uncomfortable talking about my feelings when they had to do with him. Luckily I discovered emailing him worked wonders, and we've adopted a system for the awkward talks.

Anyway, what I'm getting at is this, tell her the fact that your weekend was downgraded to a day trip does not go unnoticed, and you'd like to know why. Have you made her uncomfortable, have you overstepped a boundary, or did you just say something she finds really off putting. Make sure to mention the reason you're asking.

Not because a strange lady on the internet said to, but because you're taking the development of your friendship really seriously and you don't want to do or say anything to jeopardize it.

It's important to know each others boundaries and expectations, fumbling in the dark like idiots is a laborious and usually fruitless task.

Btw, my bf has an Oscar award worthy poker face, I thought he was a rock too, no such thing, some people are just better at hiding and or compartmentalizing. So dont doubt your charm just yet.