The D.A.'s office tells us the Quaids' lawyer said the couple -- who have been accused of skipping out on a $10,000 bill at the San Ysidro Ranch -- didn't think they had to pay the bill before they left ... they thought they could pay at a later date.
The lawyer tells us the bill got lost in the mail because they moved -- and the couple has now paid the bill in full.
The D.A. is not ready to drop the charges and will be all ears on Oct 19.
Stay tuned.