Sidney and the mobsters?

There is one thing I still always wonder about every time I see the end of this movie. I can't help but question if Sidney had something to do with the mobsters finding Billy at the hotel towards the end of the movie. Sidney was still in the hotel room when Billy briefly stepped outside on the balcony for no more than a minute. Suddenly Sidney is gone and the mobsters happen to be right there waiting for him, seems a little to convenient
. It also seemed pretty suspicious at the end when Sidney said "see you later" or something like that to the mobsters after they finished photographing Billy's fake death. Perhaps they could have paid Sidney if he led them to Billy? Anybody else ever consider this idea?