Is this just overly aggressive die polish? Or die erosion? Or planchet issues?

For a quarter that is otherwise rather well struck, the date on this SLQ is nearly missing at the top. The reverse show some weakness as well, but nothing like the obverse.
I do like this coin, bu I do not own it. It is currently in Northeast's inventory marked as "sold".
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Comments
IMHO looks like struck though grease on the date
https://photos.google.com/album/AF1QipMx0x0MY9_dYEwK5mIFUuhp4mScp9LT-jakrKwE
https://photos.google.com/album/AF1QipPWUndcm4VDbAj7kXDQjtWkPCaT3qb5Bhr9sxrk
Agree. That was my first thought as well.
Thanks to you both.
After magnifying the picture, and being able to 'read' the date, even in the weak area, I agree with the grease filled die opinion....Interesting coin... Cheers, RickO