Why did 3rd or 4th coat of polyurethane on wood floors give somebody a lift 4 plus days to dry ? My contractor says he have never seen it purloin so long. Now...

My contractor says he have never seen it purloin so long. Now it looks too thick, have little pieces of dirt adhered to the surface, and at hand are some foot prints where I walk thinking it was dry

How do I fix this ? My contractor requests to sand the whole floor and reapply another coat
Answers:    brand sure it's completely dry and lightly sand... afterwards re-apply thin coat

Be Blessed!
Did you allow it to dry thoroughly until that time applying more coats?