It also tends to appear at the end of pregnancy (last trimester). If your concerned talk to Ur dr. However Ur dr is most likely testing for it at every appointment, everytime U pee in the cup. They check Ur urine, if it has protien in it they will send u for further testing. It's not very common.
Another symptom is blurry vision or seeing spots
Dizziness, excessive swelling(feet,hands,and/or face)headaches,high blood pressure, and protein in urine woukd be the most common symptoms