prsman is prolly right. Dogs have different idiosyncracies regarding how they eat. I had a Lab that could empty a bowl of dry kibble in seconds. Most of it went down whole, which was OK because none of it touched his teeth and he never had bad breath. On the other hand, I knew an Old English Sheepdog that would snurfle around her bowl endlessly for just the right piece of kibble, raise her head and slowly munch it up. A bowl would take her 45 minutes.
There is a chance that Rosie doesn't like her kibble, or that she has a tummy upset. Labs are chowhounds, but I've seen both of mine step back from the bowl when they didn't like the food, or they had a stomach prob. If this behavior started just recently, you might try a different brand or food to see if she does the same thing. You may want to have her checked out if you notice any other changes (the runs, yakking, ability to do calculus, etc.).