Recently my 96 GMC Jimmy 4x4 has developed a small tranny fluid leak. On tracking it down it appears to be coming out of the vent tube that is right next to the tranny dipstick, from there it falls on the exhaust manifold and what doesn't burn hits the skid plate and then the ground. I serviced the tranny about 7000 miles ago and did not over fill it. I can't figure why it would do this. Anyone ever had this trouble?