Sorry for going off-topic in the GLES1 thread, but to those who are using GLES2, the BlackPawnTextureAtlasBuilder takes perfect care of you by supplying parameters that allow you to add the spacing.
If you don't know how to use it, it's as simple as:
Using java Syntax Highlighting
// Build and load the bitmapTextureAtlas
buildableBitmapTextureAtlas.build(new BlackPawnTextureAtlasBuilder<IBitmapTextureAtlasSource, BitmapTextureAtlas>(0,1,1));
Parsed in 0.030 seconds, using GeSHi
The second and third parameters set to a value of 1 will resolve the line issue.