The thing that would raise my hackles is the indignance expressed by the debtor while insisting that a duck is a goose.  Net thirty is pretty much standard, not 45.

On the other hand, I would not necessarily forego the 30 orders per month over a 45-day lag.  Then again, if I were fronting recording fees or other expenses, it might be a different story.

I think it is pretty clear that a sudden and dramatic slowdown in payments should be a cause for concern.  It is not unusual for a customer in financial difficulty to change payment habits and, ultimately, close its doors and leave the vendors holding the bag.  Keep a close eye on both incoming volume and money.  Don't let them rack up more in arrears than you can stand to lose.