I really don't understand this but I've noticed that often when I drop something into a design and then move it, the component /looks/ like it's in the right place but then when I try to do something like align a plan to its surface, it's actually back where it randomly dropped in (read: very much not where I wanted it to be)
I'm not sure if that's a bug or a misfeature but it'd be nice to at least have the option to be able to start sketching in the plane defined by where the surface of a component appears to be in a design.
Note that that blue construction plane (upper left) is actually on the surface of that mounting reference body (lower right).. or at least it should be and that's where I wanted it to go.