Linear (plaque psoriasis?) rash, or am I just seeing things?

I have had this rash (doesn't itch or hurt) that has been diagnosed as plaque psoriasis. It gets worse in late August to early September and continues to be bad through March or April.

What I notice from time to time is that a subset of these spots get very straight-line linear. The photo shows a curved "line" that arcs around my knee then straightens as it heads down my leg toward my shin.

Is it just that I have enough spots that they are bound to line up sometimes, or is this actually something diagnostic?

Has anyone else encountered this?