Normal. I've thrown up liquids thru my nose both when I've been leaning over knowing I'm about to vomit and when I've been laughing and "choke" on what I'm drinking. My grandchildren do the same.
Liquid will go up and out our nose when we close off our air pipe and get the esophagus closed at the same time. It's possible, that at 7 months her muscles aren't well coordinated yet. Does this happen when she sneezes, coughs or laughs, or begins to cry while drinking? Is she beginning to use a cup or sippy cup? All of those would cause the milk to come out her nose.
Our noses are self cleaning. You don't have to aspirate the milk out or rinse out the nose. Just give it a good wipe.
This is nothing to worry about.