One thing I can guarantee you is that they are not waiting until you are no longer watching your speeds to throttle them. If, in fact, they actually did anything, then the speeds will stay good until there is an actual problem, not a manufactured one. If they didn't do anything, and you got good speeds, then just hope they stay the same. No one is out to get you. No one is going to deliberately slow your speeds. They don't do that. The number one thing that begins to slow speeds is more people online, hence the sometimes large drop in speeds during peak times.
Again, no one is going to deliberately throttle you when you finally aren't looking.