Hard to say from the description. One possibility is a "cat's paw" of wind, a tiny little vortex. Another possibility is a local source of something oily or detergent-like that affects the surface tension of the fresh, clean water. Some beetles actually seem to use such materials for propulsion across water!

But sorry, I am afraid we might need more detailed information. Maybe someone in your area might have a better idea.

Cheers,

Jon

As Jon says, without more information we're just guessing but that's part of the fun.  So my guess: vibrations from passing traffic, made directional by the shape of the ground under the puddle.  The traffic could be vehicular or animal, including you.