What could be the cause of my puppy having milk coming out of his nose?

My dog recently had a litter of 14 puppies and subsequently she had a full hysterectomy. One of the puppies was born with a detached placenta and didn't make it and another died two days after being born, even though he was strong and healthy. The puppies have all been vet checked and I was told that they all looked healthy enough to go ahead and give them dry food mixed with their formula and blended into mush. I've been doing this since yesterday, and I'm much more comfortable with it than bottle-feeding but some of the puppies still needed to be bottle fed. It's been over twelve hours since they got formula from a bottle and one of them in particular has been occasionally having milk come out of his nose. I hold him with his head downward toward the floor (belly down of course) and I use a towel to wipe his nose off and I pat his back and use an aspirator and then he stops. But I'm just wondering what's going on. I just had them all to the vet last on Friday! And I want to call my vet but I won't be able to talk to them until later today, So I just wondered if anyone knew why this is happening and anything I can do to help the situation until I can discuss it with my vet later today.