Why can't I remove '/' after controller's name? like:www.domain.com/account/signup?fromID=8273

[eluser]lovinglgz[/eluser]
Once I updated to 1.7.2
I found I cant visit link like: http://www.domain.com/account/signup?fromID=8273

but the follow one is okay: http://www.domain.com/account/signup/?fromID=8273

seems it need a '/' after controller name.

below is my config context about permitted url chars.
$config['permitted_uri_chars'] = 'a-z 0-9~%.:_\-\?\=&%';

Does anyone here can help me?

Thanks in advance.