2009 kidney sizes r/11.7 & l/12.0 & common bile 3.7 in 2013 r/10.9 & l11.7 with common bile 4.8. Is it normal for kidneys/bile to change in size?

Yes. The measurements on ultrasound vary quite a lot. The technology is not reproducable for data like size to the sub centimeter level. It is close enough however, and your data sounds pretty normal.