Anyone encountered their dog's stool testing positive for giardia and your dog being asymptomatic?

The reason I ask is Luna had a 1st yearly check-up last Thursday (weighing in a 58lbs and appearing in perfect health. I brought in a stool sample of hers from that morning as they asked me to bring. I called the vet today since I hadn't heard anything back regarding it, and it turns out it showed she has giardia. Quinn and I were both super surprised by this as she has had no symptoms of fatigue, weight loss, diarrhea, vomitting, nothing! She does get some stinky gas in a while, but with the occasional treats she gets from us it was nothing from the ordinary. Have any of you come across this? 

I'm swinging by the vet tomorrow to pic up some medications for her to clear it up. 

- Lucie