Typically it is random. I did however noticed the battery meter jumps around. Like it would go from 92% to 100% whenever I plugged into the charger. That's what gave me hints to when it is happening. So I try to not use the plugged in browsing method anymore. Also my suspicion that this maybe a government employee misusing government resources came from the fact that I hate privacy violations. And it seems that everytime the NSA or home land security hits the news, I get these bad experiences as if I caused their troubles.