At 4.1 cm you are far away from the critical zone, they start becoming concerning as they approach 5 cms. Growth rates vary by each person, depending how slow it grows it may never get to the critical zone, you should find an aortic disease specialist (cardiologist) to consult. He/she will establish a proper periodical evaluation, the frequency will depend again on growth rates and other factors. Again, not all cardiologists are specialists on aneurysms, you want to find one who is, it will make a big difference.