Odd Concentric Circles On Two Ike Dollars

So, for some unknown reason I have a bank bag full of over 100 Eisenhower dollars from the 19070s. They've been there for 35 years -- no clue why I would stow these away. In any case, I was looking through them and noticed that two of the dollars, both 1978 (one D, one not) have concentric circles on them that even show up between individual letters. If it were a simple scratch, how would it appear between several letters forming a circle? Wouldn't the raised nature of the letters and numbers stop the circle from being concentric all the way around?

Have a look. Heres the 1978D.



The scratch circle is perhaps 1/4 cm. in from the edge of the coin. Note how it continues between the letters of Liberty, circling around the entire coin, and even appearing between the numbers in the date. Wouldn't the date, or the letters, be raised enough to stop, say, another coin from scratching the entire thing in a circle? If another coin, say, were laying on top of this coin, you'd see scratches on the date and the LIBERTY, not as much on the coin itself, no? And again, it wouldn't be the complete circle.

Here's a blow up of one scratch:



And here's the 1978 coin, this one has as many as 3 concentric circles. I've noted with a red arrow everywhere the circle pops up. Trust me about the scratches between the date numberrs -- on the coin itself you can see them clearly. I couldn't take another photo as my camera battery died.



And here's the reverse of the same 1978 coin, note the circle again:



Any idea what's up with this?