I just saw Taxi Driver for the 1st time, and I'm curious....?

In the scene where Travis is parked and his penger is speaking to him...he talks about "the shadowy figure in the window up there"...and continues to describe how his wife is having an affair...Is that guy Martin Scorsese making a cameo? I seem to think it looked like him. Thanks for any help! I loved this movie, thank you AMC network!