Strange Police experience...

I got stopped by at police checkpoint a couple of weeks ago on the way home from work. The guy pulled me over and told me in german that they were doing a random drink driving test and asked if I'd been drinking. I answered (honestly) that I hadn't and the policeman said "Fine, you can go now, have a nice evening." That was it, no breath test, no sobriety test, no "please recite the alphabet backwards while standing on one leg and flapping your arms like a bird"...

I can't decide if I've just found a really great way of getting away with drink driving, or I just misunderstood the guy (my german isn't that bad), or if Heidelberg is just a much more trusting place that I thought...