I brewed a black IPA last weekend and due to time restraints, I decided to pitch a vial of WLP051 directly into primary at 64F (my basement temp and the same as fermentation temp). The yeast strain had an expiration date of May 31. 2013 (5 weeks away, but still near end of effectiveness range). Visible signs of fermentation took around 72-75 hours to appear. Should I be concerned with this delay in onset of fermentation? I do try to practice good sanitation practices, and the fermenter remained closed with airlock during the period.