Young budgie vomiting? Help!
I need some help from other budgie owners.

I've got three young budgies (under 6 mos.) living with me. I just took them in for their first vet appointment two weeks ago, and they all got clean bills of health.

Today I let the three of them run around on the floor of my apartment, monitored the whole time. I put a little millet on the carpet and let them eat it. They picked around the carpet a bit in typical budgie foraging-on-the-ground mode, but I thought I stopped them from eating anything other than the millet (and I just vacuumed recently, so there really wasn't much of anything on the carpet).

Fast forward to now, about two hours later. I look over into the cage and Alfredo, my youngest guy, is doing something weird. He's putting his head forward and retracting it fast, like he's gagging. And then he threw up some seeds.

It doesn't look like any courtship feeding I've ever seen (I've owned budgies before)... he's just sitting on the perch and doing the head-gagging every few minutes.

Should I take him to the emergency vet? Could some tiny bit of stuff on the floor be hurting him? I don't want to stress him and me out if it's not necessary to take him to the vet. Do some budgies just vomit/gag like that without courtship feeding anything?

Help!

EDIT: Aaaaand now he's down on the food dish, eating and looking okay. I really have no idea what is/was going on.