Sometime during the night, she met Cole at a Downtown bar; though she never learned his last name, they "really connected" and decided to sleep together. McCartney fell asleep at 4:02 AM, around the time Cole sneaked out of the hotel before CTU could secure the exits to stop the spread of the Cordilla virus. When Cole did not show up in the quarantine area, she reported to Michelle Dessler that he was missing; she later assisted Dessler and Agent Ed Miller to find out Cole's name.
Background information and notes
Kathy was not showing symptoms when she was talking with Michelle, so there is a possibility she may have been one of the few with an immunity to the virus.