Dude does have a green glob of something on his glove that he kept going to
According to Cardinals minor league pitcher Tyler Melling, the answer to that question was a resounding yes (UPDATE by Stephen Meyer at 1:05 PM EST: Melling has since deleted the tweet in question, but here is a clear photo from The Big Lead on Twitter):
Jon Lester's Glove Contained a Green Substance, Was He Cheating?http://t.co/45qaEXHNjo
— The Big Lead (@thebiglead) October 24, 2013
We can clearly see something on the inside of Lester's glove, though what that may be is nothing but pure speculation.
What can't be disputed, however, is that Lester did rub his fingers on that spot throughout the game, as caught in a vine that has quickly begun to circulate around the web: