Saliva based drug test?

I work part time at a publix in an undisclosed location. I am going to be in Europe for longer than the maximum allowed time off so will have to quit and be rehired. On this trip I will be in Amsterdam and plan on... well smoking some weed. When I was first hired they used a saliva test, and from what I understand still do. Considering that I have only smoked once, and will have about 1-2 weeks in between, will I be safe? How far back can the common drug tests check marijuana?