To answer my own question (sort of), it appears to be the "seamlessly" switch. Using a different pattern that shows orientation (that looks like a "4"), I found that in the color channel, setting 'seamlessly' seems to tile out the color map in all four orientations. However, it doesn't seem to have this effect in the bump channel which is why the two misregistered. The attached picture uses a shader with an elevation mixer to show bump only on left and bump+color on the right with "seamlessly" set for both channels. The color tiles are rotated while the bump tiles never are. Clearing "seamlessly" gets everything lined up. So, I have the answer to my question. Just didn't realize how 'seamlessly' worked differently between color and bump. Is this intentional? Or a bug? I didn't see it in the bug list. Marc