I tend to weigh in the morning and mine recommends leaving 12 hours after exercising. If you weigh in in the morning, on an empty stomach there isn't much "non-muscle" stuff hanging around like undigested food (yum!) that will make the % higher.
I tend to use the body fat scale every couple of weeks, or when I get to a new "lowest" weight - I'm yo-yoing at the moment!
You say you haven't changed your eating at all, perhaps this is why you have reached a plateau, maybe just try cutting out one thing (like one candy bar or bag of chips) every day. Also try to drink more water, people say that this flushes out the system well and reduces water retention so you could lose a few % that way