help: 96 right axle pop out

my 96 civic (auto, couple) right axle pop out yesterday. dealer replaced it, and told me the old axle was either wrong one or put in incorrectly. the teeth on the axle worn out. my questions are:
1. any damage to transmission
2. if the axle pops out, does it mean that the old axle is either wrong one or put in incirrectly, (the right axle was replaced on august, i put 2000 miles before it poped out

If the dealer replaced it they would have told you if there was any transmission damage. More than likely the axle was installed wrong. I've tried putting in an axle with the wrong number of splines, didn't know it was the wrong axle, and I couldn't get it into the tranny for the life of me.