1990 was the last model year when Paul Brodie was responsible for painting Kona frames and I assume that this batch of red Lava Domes came towards the end of that, as they were the first Konas with no spatter - I guess it could be that he didn't even paint your frame. I assume that he had been responsible for the design of the colour scheme, decals etc, as it would have been natural to have made use of his talent in that area and certainly all subsequent Konas had a very different look. However it doesn't look as though the K was the work of the new designer, as the Fire Mountain pictured below also has a K but has spatter paint and is otherwise wholly in the earlier style. While the red Lava Dome has the usual TBG decal, and is otherwise in the plainer style of the red Lava Domes. So there isn't any clear pattern and maybe it was just a product of a restless mind at work. You know what these artists are like!
Incidentally, Paul was also responsible for the finishing of the frames, including all braze-ons, and the brake cable guide on the seat tube is typical of his style of work. I guess that does suggest that he was responsible for the frame in the picture, although it still doesn't exclude the possibility that it was painted later and by someone else. But maybe he just got bored with spatter?