DUI and License Question?

I was pulled over and arrested yesterday for having a missing headlight. The officer inquired if I had anything to drink that night and I told him yes. In total I had about 40 ounces of beer and the last drink was approx. 2 hours before driving. The officer never confied my license and I still have it. Does that mean anything significant for my case? I ped all of the field sobriety tests and was in no way impaired. I wasn't even pulled over for swerving or reckless driving!! The officer never showed me what my BAC was even though he claimed it was at .18. I was wondering also what I would maybe want to do in regards to this problem. Thanks!