You may want to check on the chainring to see if it is replacable. I just learned that my Dahon Curve's chainring can't be swapped without swapping the whole crankset as well.
Your model may be different, though.
http://www.bikeforums.net/showthread.php?t=426753
I'm glad you enjoy your Dahon! Sounds like a great day trip for your first ride.