My toddler is obsessed with chocolate milk?

It's up to you whether you want to make it a battle or not. Honesty, we don't even have chocolate syrup in the house, because I've never seen the reason to add sugar to their milk (mean mom, I know), but I am not against it if it works for you. No, I don't think she will just "get over it". If you have no problem putting a few drops in, go ahead. If you are trying to cut the chocolate milk habit altogether, throw the syrup in the garbage.