Passed breathalyzer but don’t know how

Yes I fucked up and will never repeat it again but last night I had about two shots of tequila, a cocktail with a single shot, and a couple sips of beer and about 2 hours later drove me and my friends back home. This was my second time ever drinking and I didn’t feel anything so in the moment thought it was a good idea for me to drive. On the way home there was a roadside alcohol screening and the cop pulled me over saying that he smelled alcohol in the car(tbf it was probably my friends because they drank a lot more than I did). I did the test and somehow it came back as 0 and although I’m thankful I’m also confused how I did. Did in some way the machine mess up or did my body somehow get rid of all the alcohol in that time? I’m still confused. I’m about 6 feet and 180lbs if that matters.