Just going about validating my site with the W3C validator some more, and came across another validation issue with Gravity Forms.
When including the anti-spam honeypot for form validation, I was able to pass W3C validation, but with a warning, that one of my form fields had a < label for="input_3_8" >, but a field with that id didn't exist. I did some digging, and found the problem.
On line 1233 of common.php, you have:
return "<div class='ginput_container'><input name='input_{$id}' type='text' value=''/></div>";
which returns no ID for the form, and a wrong name. ( name="input_8" )
So, I edited it to look like this:
return "<div class='ginput_container'><input name='{$field_id}' id='{$field_id}' type='text' value=''/></div>";
and it returns the proper information, and I am getting no more validation errors with W3C validator.
Just thought you'd like to know, instead of having to track this down yourself.