If all works fine, you don't *need* to. It's just a bit nicer.
You will also see a new release of `piston` quite soon.

Once you updated piston, you will probably see a couple warning messages. That is because most of piston's "library"-sh functions have been moved to python-steem. You can upgrade you code afterwards by simply replacing

    from piston.XXXXX import YYYYYY

to

    from steem.XXXXXX import YYYYY