He actually had no idea what was happening on Earth. After all, he couldn't keep his eyes on little Midgard at every moment, constantly watching a bunch of weak mortals eat and drink. He wasn't that idle, nor was he that bored.
During this time, he had only taken a cursory look to make sure Thor was still alive and nothing was seriously wrong. That was about it.
If he really knew everything, watched everything, and could receive every bit of information, he wouldn't be the simple guardian of Asgard he was now. He'd be an all-knowing, all-powerful supreme being.
"What happened to Thor? He's nothing like the God of Thunder anymore!"
Heimdall thought of what Thor had been like lately and felt utterly baffled, even speechless.
Playing cards, spinning tops, going crazy every day, shouting things like "My fate is mine to command, not Heaven's," playing video games, cursing people out, watching anime, following new series, watching movies, reading novels, running ten kilometers every day, doing a hundred push-ups and a hundred squats, and constantly complaining that he still hadn't gone bald...
In short, the Thor of today was nothing like the Thor of the past. He had completely immersed himself in Earth's entertainment and no longer resembled the God of Thunder at all.
"Great King, you must have miscalculated. I hope it's not too late. I hope Thor's just temporarily given up on himself!"
Heimdall hadn't paid much attention to what was happening on Earth. His gaze was mainly fixed on Thor. Even then, he only checked every so often to make sure Thor was all right. He didn't know the details, or why Thor had become like this.
No, actually, he thought he understood. He'd happened to see Thor kneeling before Mjolnir that day, looking utterly lost.