This is a good reason why collectors should not buy coins on-line that only have photos of the coin in these 2x2 holders. That little thin mylar film hides a lot of imperfections.
Your link is for a SMS Quarter, not a Satin Finish. They are two very different coin finishes. The link you provided also list the coin you are referring to as a DCAM. I have never heard of a Satin Finish coin having a Deep Camero appearance. The two finishes conflict each other.
This is a very nice coin, but I agree to the suspicion of being polished or from a polished die...the breast feathers are not very defined at all on the reverse. I sent one to ANACS in 2014 very similar to this but much better defined and with a minor die crack on both sides. It was out of a mint set and came back MS65...Spark
The description from the link and I don't see a DCAM grade only SP grades. The special finish for the 1964 SMS Washington Quarter is characterized by a nice, smooth, satin-like finish. The fields are usually well struck, very clean and tend to come without any major nicks or scratches. The edges for most 1964 SMS coins also tend to be square and sharp. The bust and legends are usually highly detailed and sharp on most examples, especially when compared to circulation strike coins. The surfaces are non-reflective compared to proof coins of the era, yet, are not the same finish as regular issue coins from the same year.