It's great that you stayed in communication with her about dating her friend and all, but next time don't ask your girlfriend for a recommendation on a restaurant to take someone else out. That comes off as kind of asking her to manage your date for you, IMO. That is something that I would see old, established couples doing when they know each other very well. Manage each of your own relationships separately. Plus, your girlfriend may be the type of person who wants the honesty and knowing what you're up to, but not have every detail in her face! TMI, you know? Just keep her informed of enough so that she knows you are seeing someone but don't give her details unless she wants them.
The world opens up... when you do.
Oh, oh, can't you see? Love is the drug for me. ~Bryan Ferry
"Love is that condition in which another person's happiness is essential to your own." ~Robert Heinlein