Hello, I just received my new macbook pro 15" the other day and i finally charged it to the full since i got it and yesterday i unhooked the charger off my laptop and i started using it with a full battery. I am seeing that my time remaining on the upper right changes drastically for example it will go from 4:47 to 5:25. Or when it was fully charged it said 6:50 but then sometimes shot all the way up to 8:01. The battery itself is keeping charge no doubt about that but, im just wondering why the time keeps changing on and off. Is this supposed to happen?