FWIW, this pair of examples differs from the others in this section
as they were both explicitly okayed in the first version of PEP 8
<http://hg.python.org/peps/rev/4c31c25bdc03?revcount=120>::

    - Use your better judgment for the insertion of spaces around
      arithmetic operators.  Always be consistent about whitespace on
      either side of a binary operator.  Some examples:

          i = i+1
          submitted = submitted + 1
          x = x*2 - 1
          hypot2 = x*x + y*y
          c = (a+b) * (a-b)
          c = (a + b) * (a - b)

My guess is that this is still the intention?