Like others have said, it isn't your record that determines DQs, nor is it your average across all your matches. Instead, it is the scores (game differential), the opponent, and whether or not 3 individual matches are scored as strikes.
Were you told which matches were strikes? I believe that is normally supposed to be done. In your case, it appears there were 2 clear well above threshold strikes, those being:
- second singles win, 6-3, 6-0 win over a fairly high rated 4.0
- last doubles win, 6-2, 6-1 win over two very good 4.0s playing with a good 4.0
I'd be curious what the other strike was.