CF Carrier testing?

Has anyone else had this testing done? I was told not to eat or drink anything 30 minutes prior to my appointment this past Tuesday. I had my last sip of water at 5:28 and my appointment was at 6, but they called me back early. The nurse asked me to start spitting in this tube and asked if I had anything to eat or drink, I said not since 5:30, and she had me proceed. But by the time I started spitting in the tube it was probably only 20-25 minutes since I last drank water. Will this affect test results? I hope not, otherwise I will be annoyed at the nurse because I told her when I last drank something and she had me give my sample at that point anyway. Any feedback is appreciated!