They had a strategy going into the series because there were rumblings about the Astros and sign stealing. I recall some whistling that might have been signals and Strasburg legitimately tipping and then correcting it. I think the Nats used a rotating sign designator system which stops any sort of sign stealing, whether legitimate or relayed video like the Astros used. Its kind of amazing to me that it isnt a universal and standard practice between catchers and pitchers with todays technology.
Freegards
Yes, Aaron Boone complained about the whistling in the ALCS.