Possible Error / Strike Error?

Looks like the die had a very slight tilt, that made a thicker area on the rim of the coin. We often see a bit more tiki and it creates a fin on the outside part of the coin. It is most of the time flattened. But yours may have done this, just can't tell from the image. But this can make the coins rim thicker. But not an error that gets noticed. The one that does is the thin fin that is there, but usually flattens during rolling or in circulation.

Enlarge image and note the thin area above the rim. When they flatten, they are just common coins. Hope this helps.

That may have been the design that year. The best way to check to soo on other examples.
Or the master hub was spreading outwards. This happened on the master hub on the 1968 cents from all mints. All were affected.
Or if we see not the same thing on other examples, perhaps it was die wear on just that one die.
So sometimes it takes detective work to see what happened that year. I'm limited as my computer can't get online. I'm dealing with a tablet now. But chances are, it is normal. ( just a hunch) otherwise I would have probably heard about this before. I'll see what I can find and get back to you.