In using tags and creating searches based on tags - I have run into some issues.

Tag Tree Example

Tag Set 1
     Parent A
          Child A1
             Child A1a
             Child A1b
                 Child A1ba
                 Child A1bb 
             Child A1c 
          Child A2
      Parent B
          Child B1
             Child B1a
             Child B1b
             Child B1c

In the above example - when I search for anyone tagged Parent A, I get every contact tagged Parent A and I get every contact tagged with any of the Children of Parent A. This is what we want, so its great. However, if I do a search for Child A1, I only get results for Child A1 and not the tags that Child A1 is the parent of.

Is this the correct behavior? Can we change it?