Shimmering textures prob (not overlapped)

I'm making a texture that uses brightly colored gridlines. For some reason they sort of shimmer and wiggle as you move around the applied texture. It looks pretty much just like overlapping textures, but I'm certain that's not the problem. Any idea what's up?

Some details...

The shimmering is worse from a distance
The shimmering eventually stops. I can't figure out why though.
Only the gridlines shimmer, the other images in the texture don't.
The shimmering is lessened if I use low rez textures
Once an texture stops shimmering, it never does it again, even if I clear my cache

Happens when using high resolution textures with crisp edges. Severity depends on the quality of your graphics card sometimes. Gets worse as you zoom out or look at textures at an acute angle, because of all the pixels getting squashed into a small area with no aliasing.