I know the feeling

I think Oliver would waken anyway but because he is so snotty it's hard to breathe so I have been feeding him to unblock his nose. I also think that if they have a sore throat (you never can tell), esp with the heating on which can be drying, offering water rather than just pupd/patting etc reassures me that they are not getting dehydrated.
You can give water instead of formula - if you know she doesn't need the calories, etc then water is good. We used to do it with Murray who quickly learnt that it wasn't worth wakening for (he would often not waken the following night, and when I was consistent with offering water, or his dummy only, he stopped wakening as much).