How badly will marijuana affect my drug test?

I quit smoking about a month and a half ago in order to pass a drug test at work.. Becuase they took so long to test me I dodnt think it would be a big deal and took about 4 hits of weed over the past week , the last 2 hits were 4 days ago and i got drug tested today, it was a mouth swab and ive heard those dont detect very much but im wondering if the little amount would cause me to fail