DOA tube from Audio Research

I just opened a matched quad set of 6550 tubes I bought last year from ARC and one of them is DOA. How can this have happened? I thought they were the most highly screened and tested tubes available. Has anyone else ever had this happen? I immediately called their support line and got the support guys voice mail saying he is on vacation. This is really frustrating. I've been waiting until I had some spare time to listen at length to the KT88s I put in last year before I switched over to the new 6550s. DAMN IT!!!

VPI Classic, Rotel DAC, ARC SP17, ARC VS60, Golden Ear Triton 2s, Nordost and Shunyata. A reasonably decent system that I rarely have time to listen to.