Do verbal goodwill waiver stand in court?

I'd like to put in scenario. Party A enters into a monthly payment contract with Party B. Party A pays monthly the ammount. One day, Party A is unable to pay the monthly installments. Party B says it's fine no problem, this was verbally recorded. Party A later resumes back the repayment. Months later, Party A and Party B has an argument. Now Party B wants to take legal action on Party A for the non payment several months ago. Does the original 'No Problem' good will waiver from Party B holds in court?