Yes but trust me it's there
Alicefelldown posted pics of her birds that were first generation directly from Jubaby and one had green legs so it's hiding there.
I don't think it will be that hard to get rid of personally. I saved my 2 that hatched with green legs because I can use them to test breed others to see if they are carriers. Half of the chicks should hatch with green legs when breeding green legged x carrier. I can easily weed out any carriers that way. It sucks but it is what it is.
My first few generations hatched nice slate before it happened...I'm sure others will eventually experience the same
Trish