Wyeast contents that you should not need a starter. Mr malty contents that you would need about 167 billion cells. You're probably OK.
If you have a lot of diacetyl, fusel alchohols, esters, sulphur, or if your FG is higher than what you expect, consider using a starter. Since there is some disagreement about the pitching rate, you may find some diacetyl, fusel alchohols, esters, and sulphur; however, this will probably not be enough to ruin your beer. If you want the beer to be cleaner, pitch with a starter next time. Temperature control and aeration are also a factor.
Bottled: Old Freckled Men, Berlin Mart Cider, Creamer Ale II
English Mother****er, Do You Drink It Pale Ale
C4 Pale Ale (Centennial, Challenger, Cascade, Citra hopburst)
Gone: Honeybadger Wheat Ale, Bad Amba Jamma, Badder Amba Jamma, Slam Dunkelweizen, Creamer Ale I, Robust Porter