What brush settings did I use for this effect?

I'm going nuts with this issue.

I was working on an illustration with Photoshop CS5 and had built my own brush, which is just three fuzzy dots.

Somehow I managed to set the brush settings so that the three parallel dots formed a path that made concentric circles when I drew a circles with it.

But I lost the settings... and now I can't figure out what the settings were.

The attached graphic clip shows the concentric effect I'm trying for at the bottom and a sample of the incorrect regular setting at the top in red.

Any help in resetting the brush to make concentric circles would be much appreciated!

THANKS for any help!