I'm chosing to blame this on Cheryl Oberle and Barbara Walker, rather than Denny.
As I get into the zen of it, as I get more familiar with the lace pattern of the Highland Shawl, I'm able to think more about the shape of the stitch patterns, rather than just trying to figure out what comes next in a row. And as I do that, I think about what might happen if I do a left-leaning decrease rather than a right-leaning decrease, or what might happen if I put the yarnover before rather than after the decrease... and hey presto! I'm designing lace.
The Highland Shawl continues apace, and with it, in red, you see the start of an idea upon which I am noodling.