How do i know if my 9 once co2 tank has a leek?

i normally use HPA but when i want to shoot and im not at the field i usually fill my co2 at mc sporting goods. well, at our last big game i needed more air so i acrually used the co2. it was sitting on my back and i could hear hissing, (the leek) then a guy tells me it was spraying co2 out of it. it was a while ago so i dont know if it was the burst disk or not. i dont know how old the tank is. i do know that my couzin used it on his tippmann pump. i forget what model. mabey the tank is around 10 years of age. help pleese