readline expansion: 'cp $v/<TAB>' -> 'cp \$v/' (no expansion) - why?

[Jason Vas Dias]

my #1 bash gripe is that newer versions do not
expand command lines containing '$' in emacs
readline editing mode.  I used to be able to do:
$ export SRC=../somedir
$ less ${SRC}/<TAB>
(<TAB> meaning press horizontal tab key )
and emacs mode readline would expand,
displaying the contents of ../somedir .
Now it changes the input string into
'less \$SRC/' and prevents tab expansion
as would be done without use of any variables.
Would anyone know how to restore the old behavior
with bash 4.2.2 + readline 6.2 (linux ubuntu 12.04) ?
Thanks & Regards, Jason