Judy, you are not doing anything wrong. Even though I teased you and said that I would have to take your quilt for evidence, the fact of the matter is; many, many of the award winning and recognized wholecloth quilters use colored threads on their quilts. Especially if they are also doing some trapunto in it. Using a different colored thread shows more and can draw the eye to a certain section. The tradition of wholecloth dates back to a time before spooled treads were available. I could be wrong here but it seems to me like I was told many many (I'm old) years ago that the reason the first wholecloth quilts were made with the same color of tread is because the quilters would take peices of tread from the fabric to use for the quilting tread.
You go girl....
Hugs, Gail