Wouldn't the first cop do the DWI test?

I was at a gas station. I went there because I left my debit card a few hours earlier. I live a few blocks away and I never drive and drive, but this time it happened and it was stupid. Anyway, I backed into a car, but didn't cause any damage, however the other person had made a report and a cop came because it wasn't her car. When the cop arrived, I was outside my car. He didn't ask me what happened and I wasn't stumbling. I know that. He must have smelled the wine and called another cop to do the DWI breathalyzer. Just wondering if the cops handled this situation the right way. And he didn't see me drive either. Also, the witnesses don't live in the same state and were visiting.