Hi nabber,
Thanks for the title.... queen of helpfulness
Usually when an impacted tooth is removed, some of the bone is removed as well. Also if the tooth was infected, then some bone is removed then too.
It is a good sign that the lump has gone down in size and that no pus was evident and that you feel good. The residual tenderness in the center of the remaining lump may be normal at this stage. If the tenderness and the lump does not go away completely within a week or two, then see the dentist. Of course if it gets larger or more painful, don't wait to see the dentist and yes have an xray done at that time. Ideally it should continue to dissipate and be gone in about a week or so.
Hope that helps!