JUST FUCKING RELAX!
The manufacture of the swab test states on their own web site:
"Saliva drug test will reveal only current or very recent (within the past twelve hours) marijuana use, but saliva drug testing kits will detect use of cocaine, opiates, methamphetamine and ecstasy over the past two to three days. . ."
Information about saliva drug test screening.
So just fucking chill.
You'll be okay.