Hernias do tend to get larger over time. Things that tend worsen hernia are things that increase pressure in your abdomen such as chronic coughing from smoking, difficulty urinating in men with prostate problems, straining to have bowel movements due to constipation, repetitive heavy lifting in construction workers or body builders. Obesity is another risk factor that worsens hernias.
If your hernia is not causing symptoms, there is no emergency to fix it. They will get larger over time, and you run the risk of developing a bowel obstruction if the intestines get trapped in the hernia. Hernias are also much easier to fix when they are smaller. The bigger they are, the larger and more complicated the operation.