First, I thought "fair use" was primarily a copyright notion. To the extent "fair use" applies to trademarks, they don't allow bastardization of the mark which is what Mike is complaining of.
I'm only familiar with a few "fair use" type cases in trademark law (although I'm not sure they call it "fair use" in trademarks). They generally pertain to references to another's goods/services. For example, some imposter fragrance said theirs smelled just like Chanel No. __ -- Chanel sued but lost since the imposter was using their trademark to refer to their product. To prevent the imposter from using the trademark to refer to Chanel's products would wreak upon us the difficulties brought about by the Artist formerly, and once again, known as "Prince."
However, the imposter didn't have the right to butcher the mark by changing fonts, adding/modifying graphics, etc.
As a trademark owner, you have the right to prevent others from using your mark on similar goods/services sold by them. I believe that includes resellers. They should be "under license" to use your trademark.
The whole point of a license is that you allow somebody to do something you have the right to prevent them from doing. The license can have conditions on it. It ought to have strict guidelines for use -- including fonts, size, orientation, graphics, etc.
There's a thread in this forum regarding getting permission to use the NFL trademark(s). I'd be curious to see what style guidelines are attached to that license if anyone has it. Their website might even publish those guidelines.
Your trademark can be a valuable property right and you should take steps to protect it. To some degree, the cat's already out of the bag. But you should take steps to get the distributor under license. You may have to threaten getting a different distributor if they won't comply.
As to "it's just not important yet," that's just plain wrong from your perspective. You are now building value in your name and it's very important that you build strong name recognition in the purchasing public by consistent use. In addition, a large portion of the value of the mark is in the designation of quality by the mark. Why does anybody buy more expensive Kleenex(r) tissues over generic facial tissue? It's because they want quality tissues and "Kleenex" (to some anyway) means quality. Any sloppy use of your trademark harms the value of your mark. This distributor is hurting your property rights and you need to stop him ASAP.
I hope that helps.
Regards.