Re: awkward moment
I'm a little late to this party, but better late than never.
First, there's nothing wrong with masturbating to this/her. Fantasies and thoughts are private matters, no one can tell what's going on but you. What she did WAS arousing, afterall, and masturbating to it relieves a lot of the sexual tension it caused. No harm done..
Second, if you're aroused by her (which you are) you're more likely to read things into stuff. The power of emotion, and all. That doesn't mean she might not be intentionally doing this stuff to you, mind you, just that it's going to be supercharged due to your arousal.
Thirdly, I think it a bit inappropriate for a six year older girl to be doing these provocative things, even if she thinks they're 'cute' or 'harmless' because you're 'so young'. It sounds condescending the way she treats you, especially since you're picking up some erotic cues. Likewise, eventhough it feels good, there's a part that doesn't. You might consider asking her to please stop, even if you enjoy some part of it, it might not be so okay for her to take advantage of you here.