So I brewed my third extract batch last night. It is a pale ale and|I decided to use white labs (California Ale yeast wlp001) for the first time. I followed the instructions, sat it out for several hours before pitching to get it to room temp, aerated my wort before, shook well, and pitched at 70 degrees. The best before date is Mar. 2012 and it says on the bottle fermentation will begin within 5-15 hours. It has been 15 and there is no activity whatsoever and I don't just mean the airlock, there is no foam or krausen (sp?) forming. The only thing I can think of is that maybe the yeast didn't get down to room temp like I thought it did and that is causing a slow start....
Should I be worried or is it still too early? What should I do?