Report Builder matrix column headers replaced with record data from the table

Wow this is a new one.  Whilst working on Report Builder report (DAX querys) the main matrix object in the report body is now filling some column headers with record data from the queried table.  Bizzaro!

Matrix column header names replaced with record data from the queried table!?

Red arrows point to column header name replaced with actual column data!?

 The report state before run

And realise that the rejig of the report underlying querys when plugged back in I made the mistake of choosing the columns as the headers.  Which is possible?  It is a column header wouldn't the name be automatically inserted when the column was selected?

Anyway problem solved as I was writing this post just had to over write the header name in text.  Weird stuff, no wonder I was getting weird results.  Submitted post for posterity.