good call surrey...
even still, i personally would chance it, and just check every week or so, for play, as long as it's not binding up, at full droop, it shouldn't have spontaneous failure... but danger is my middle name...
that being said, regardless of your shaft, you should be checking your u-joints for play before taking ANY wheeling trip, or long road trips, along with checking tires for abnormal wear/cuts in the sidewall, all of your balljoints and tie rod ends, pitman arms, radius arms, shocks, and all of your applicable fluid levels... though it's much easier said than done... last time i checked my front diff was when i changed the fluid... lol