Not necessarily. It might just be bypassing the congested route that everyone else on your ISP is using. Comcast and Verizon have had disagreements peering with Cogent, one of Netflix's ISPs:
http://gigaom.com/2013/06/20/verizon-that-peering-flap-about...
It's not throttling, but rather the peering points along the "best" route between Cogent and Comcast/Verizon are overloaded, resulting in lousy connections between them. Look at this traceroute hop from Comcast to Cogent I just recorded:
7 he-0-10-0-1-pe03.111eighthave.ny.ibone.comcast.net (68.86.83.94) 21.377 ms 20.379 ms 19.387 ms
8 be7922.ccr21.jfk10.atlas.cogentco.com (154.54.13.161) 67.126 ms 67.747 ms 69.083 ms