Brenna, I've heard that as well.
Babies need to eat so often because they are on a liquid diet, so they digest the food soooo much more quickly than solids. i've heard nurses suggest that you simply feed them as often as they like -- and i've yet to hear that you should actually add cereal to their bottle (though of course, that doesn't mean that it's not okay!). I would ask your doctor about this one -- perhaps Eva is just ready to start taking in some solids before her bedtime feeding, and that itself will tide her over a little longer into the night. but i'd definitely check in with the doc -- just to get a professional opinion!