magnepan -extremely fragile tweeter

Recently purchased a pair of maggie 3.6 . listening for the first time and only 1 hour of classical music in low volume with moderately high powered amp( Accuphase P500L, 400 in 4 ohms) I noticed the tweeter is not working properly . Following a thorough inspection I noticed that tweeter at some location is over heated ( not completely burnt) and making buzzing noise!!! I previously had Maggie 3.3 and was very careful not to overheat the tweeter but it happened. Very disturbing and frustrating experience. Has any one experienced the same problem?