Most likely grease in the die effect. The L in Liberty, the US in trust are also shallow. Metal cannot enter the die when there is grease trapped inside. One tell tale sign of this is a bold letter next to a weak one.
Not really. It really is a fairly common effect. Most collectors call them business strikes, as they are just your run of the mill coins. Made to spend and use by the general public, who reconize coins by size and color. Most collectors want a coin that has nice sharp and defined details. That is why the mint makes proof coins.
You should post complete photos of obverse and reverse when asking to have a coin evaluated. Full photo front and back. I noticed that the 72-D has a misaligned strike.
