I'm the same height as you and 4 pounds, which is a bit over 2 kg, makes a huge difference on my frame, it's almost a whole dress size.
You are still in the right range for your weight, but I can understand your panic. Just eat healthily, exercise and don't weigh yourself for a whole week. Measure your waist, thighs and arms with a tape measure and write it down, and then measure it all again in a weeks time. If there is no change think back to what you might have done wrong, an unhealthy snack or too many beers or something. Also just look for tone and flabbiness, you might find that's improving while your weight stays the same.