never come across a spirit who did, but i wouldn't listen if i did meet one as spirits do lie and the spirit you heard this from was probably wanting to scare you or keep your attention because it wanted to talk. most spirits were human and humans will lie or fabricate things, i wouldn't worry.
doomsday theories and death clocks do not scare me, my view on life is many have a destiny, something they need to fulfill, but the path won't be a straight one. each decision alters the path, it might lead to the same place, but your choices will shape the outcome of your life. if you were told you would die at 24, you've already begun on a different path. if you decide to take this warning to better your life, be healthy, work out, you probably won't die at 24. overall, i wouldn't buy too much into it. if you are worried, ask in the fortune telling forums for a reading. someone will probably give you one for free.