A flippant, but true, response.

Almost every time a sender I'm talking to is dealing with a Spamhaus issue, they ask me, "Why now? Why did I get blacklisted today, when I've emailed this very same list three times previously." The answer I have, might be kind of flip, but I think it's appropriate: "Do you get a ticket every time you speed?"

Maybe your data changed, but maybe not. Maybe you drove too fast in the wrong place at the wrong time. Maybe nobody else being watched that day drove too fast through the speed trap. Maybe it's Thursday, and maybe Spamhaus watched a different set of IPs this Thursday. Who know? They're not going to tell either you or me. They probably don't even have a useful answer themselves.

Have you ever tried telling a police officer, "But I drive down this street at a hundred miles an hour three times a week. Why are you only ticketing me now?"

Just like that police officer aiming a radar gun at you, a Spamhaus listing is typically not an automated process. A real live person had to manually review spamtrap hits from a certain IP address on a certain day, and it is probably true that they're not watching every single IP address twenty four hours a day.