The attached screen shot shows the problem. The toolbar icon circled in
red is one used by gnus, which I just finished using to read mail. The
bottom window shows the value of tool-bar-map, which indicates that a
"Paste" icon should appear.

I've noticed this problem for several weeks. Unfortunately, this is on a
new setup for a new machine, so I'm not able to come up with a change
that possibly triggers the problem.