i would suggest that you just leave it alone? does she know how to reach you? cos if she does then definitely leave it alone.
it's kinda not fair to your new girlfriend either, cos then you probably aren't over her.
in any case whatever you do, do not call her, email her if you see the need and are going to do something regardless, something like hey i thought i saw you the other day? was that just me or did you see me too and laugh about it throw in those stupid lol's and sound like you're ecstatic about life. and don't say anything personal or ask any questions about what she's doing. AT ALL.