Another Contract Question - 45 Days?

Here's another question brought up by my writing group.  The majority of contracts state an author will get paid 45 days after the end of each quarter.  However, we've discovered that publishers have different ideas as to what constitutes 45 days.  Some will pay within (or at least have the statements delivered and/or the check in the mail) within 45 straight calendar days (which, for fourth quarter statements, is around Feb. 15th.)  However, there are other pubs who pay within 45 business days (deleting Saturdays and Sundays), which makes checks due around March 3rd.

If the contract does not state specifically "business" days, is the author to assume payment will arrive around Valentine's Day?  Or is this something that needs to be addressed?