Put your testosterone in check dude...
It MEANS:
Wow, there is someone I remember from my past. I am curious about him. Has he changed? Is he more, than i thought he was then? How coincidental meeting him on here!
Half of it is surprise for her. The other half is curiosity. You need to quit humping her leg!
If you want to hump her as you call it, relax.
I would suggest, setting up a date. She did give you the digits right? Act as if you just want to check her out is all, see if she has changed. Don't get all hardcore on her from the get go tho.. you'll scare the hell out of her, and she will slip away.
Be more cool than that. Don't act desparate for a quick f@ck.
Spend a little phone time. then make sure you follow it up with being in person.. If at any time during this process she gives you excuse ( I have to stay home and brush my goldfishes hair blah blah blah) Then ignore her. At least for about a week. After a week, send her something. Maybe have a floral shop send her a teddy bear or something, but stay away from flowers. Give it a day or two to see if she is going to call. If she doesn't, then call her, but briefly, say, I Just was calling to check if you got _________ I hope you like it. She will say that was very nice of you. All good, but then you just set up the next date. by now she will suspect you are into her.
If she starts acting all lawdy dawdy at any point during this process, just zip it. I mean give her the silent treatment. Be a man of few words.
What i am saying here is find ways to peak her interest and keep her off guard. Be sweet. Then be kinda cold. You are being unpredictable and thats good. Curiosity is whats driving her, not lust to boink you. You have but one chance to sway her your way, and she obviously responds to curiosity so make her even more curious!
It shouldn't take too long, until she has made you sort of a habit. And damn... habits are hard to break aren't they?