[gonzo]

Recently I was looking through a box of cards I collected back in the 1980s, and I found these 2 1987 Topps Dan Plesac cards. 35 years ago, I pulled these cards from packs as-is.

At the time, I noticed that one Plesac looked like he had a rash on his neck, while the other didn't. I just assumed it was a Topps airbrush job on some unsightly heat rash, but I didn't think more of it. I put them next to each other in the box and pretty much forgot about them until ran across them this week.

I tried a couple of Google searches and I didn't see anything similar.
Have any of the 1987 Topps collectors here seen this before?
Does it look like an airbrush job? A printing ink oops? Or something else?