You should definately follow up. Otherwise you kind of look like you don't mind. Make sure its polite and professional and don't jump to any conclusions. Keep

You should definately follow up. Otherwise you kind of look like you don't mind. Make sure its polite and professional and don't jump to any conclusions. Keep records of any correspondence and activities related to the matter so that you can helpfully point these out at a later date should you need to. If it happens again then you need to be more firm and notify them of your intended actions which could include finding other employment. The real reasons for the late payment could be many: no money to pay you, bank administration problem, forgot to do payroll. There aren't many acceptable reasons and if it is "no money to pay you" then I'd start looking for another job.