Are 'had,' 'quick,' 'correct, and 'found' correctly used in my sentences?

My friends said that I must have asked my new girlfriend follow-up questions if she had given vague responses to my questions. They also said that I must have been quick enough to correct certain responses from her, which I had found erroneous or questionable.


"Must" is not right. You need "should."


Thank you, Englishmaven.