Most Helpful Girl
If you like her, and she likes you, then why not show her you're interested? I know guys are advised to play it cool, etc... but if you're genuine and so is she, then it isn't a game. Leaving it a week? She'll think you're not interested or playing her. I would call with the reason of telling her you had really nice time and you'd like to do it again some time. If she's genuine she'll appreciate it. Least that way you'll know where she's interested in YOU and that it's not just all part of the chase/game.