For most Aneurysm's they generally grow about less than 1/4 of a centimeter a year, if you're young like me - this may help with your anxiety!
1/4 x 4 = 1cm (or about 1/2 an inch)
Generally speaking, they don't show any symptoms unless they are very large. (Around 4-5cm.) however just for the purpose of lets make the size 3cm. Now ... to get to 3cm's if it's growing at that rate would take about 12 years.
(And this is the part that should put some minds at ease!) Its as simple as subtraction. For me if it took twelve years to get to 3cm, that means that I got it when I was 6 YEARS OLD. Now how insanely silly does that sound? Considering these issues generally affect older people with health issues such as high blood pressure.
So now, every time I feel a pulse in my abdomen I get a little nervous still, yes. But this puts things a bit more into perspective.