Born to those who have thrice defied him, born as the seventh month dies. He didn't want that to affect his, and especially Hermione's, relationship with her parents. It was almost like listening to Sybill Trelawney.
Actually, hold on, can you write that down. That last line Severus spoke with so much foreboding that it chilled her bones. The one with the power to vanquish the Dark Lord approaches, born to those who have thrice defied him, born as the seventh month. It was a relief to see the end, but building a big model is a big investment of time, and for that to be over.