I have a similar suspicion, aristotle. At the same time, depending on the details there might be something here (where there'e smoke, there may be fire.) I'm hoping we can use this thread to get into more solid analysis of what people are seeing.
For example, a few years back someone reported that his traffic went to zero every day once it hit a certain number. He shared his analytics with me in private, and that was most certainly the pattern - no matter what time of day, once Google Search traffic hit that number, it fell to zero for the rest of the day (until midnight local time.)
That was the strongest evidence I've seen for traffic shaping. Would love to see something that solid relating to zombie traffic, too/