It is not a problem per se, but typical 'behavior' of the lavender mutation. Since there is very little info on breeding lavender, I can only tell you my thoughts on it. Most of the first pure lavs show this, as well as recent crosses back to black. You just have to select against it and get to a point of breeding good clean lavs. The lavs are a project, so in my opinion do need work, but there are not many folks dedicated to putting the work in. The fretting is really the least of the work that should be focused on with such a project. Color is easy to obtain. The focus should continue to be on breed conformation and getting more lines to standard.