It sounds like the burst disc (aka safety valve) was installed incorrectly and is leaking. If the disc had burst due to excessive pressure there would be a sudden release of all the co2 in the tank.
I myself would be comfortable tightening the disc, but I have replaced them before myself and am willing to take the chance. If you do it wrong at best the tank will leak and at worse I guess the safety wouldn't work at all and if there was a problem the tank would explode.
If your not comfortable doing it yourself go back to a paintball shop and ask them to check it out for you. If it is the disc it shouldn't cost more than a couple bucks to replace and they should be willing to do it for you for free (especially if you buy the replacement disc from them)