You may accidentally have uv repeat on.

Go into your shader's attribute editor, from there click the little arrow-box beside "color" which will bring up the file. You know this -- its where you assigned your texture.


Look down at "UV Coordinates" maximize that menu and click the little arrow-box. "repeat UV" -- if done right -- should be 1 and 1, likewise with "coverage". Maybe a couple other things, but those are the two most common.