Ouch man, I just smoked an Opus X Robusto yesterday and wasn't thoroughly impressed by any means. I can't believe that happened, never seen that before.
Had this happen to me before and it still smoked fine. I hate seeing it but the good thing is that is was still enjoyable. Hope it turned out ok for you,,,Opus is my all time favorite cigar.
That is horrible I had the same thing happen just the other day with t52. I went outside into the cold and just like that two cracks. Major disapointment, still smoked nice though.