Drug Testing

I have found and been offered a wonderful job! Today, I stopped by to do some paperwork and give them a urine test. I am not one to take any meds. I rarely even take Tylenol! Well my test was negative for everything but opiates. For opiates there was no reading one way or another, so, they are sending it out to a lab to check on it. I feel so worried even though I know I never take anything. I've heard where poppy seeds can throw this off, but haven't even eaten poppy seeds that I know of. My husband and I went out to a restaurant last night, but don't think there were poppy seeds in anything. I'm hoping the strip was bad, but has anyone heard of a false positive happening from something I'm not mentioning? What if it came back positive when I know I haven't done anything? I would hate to lose a job unfairly! Thanks.