I think you're right - but it used to be background information/recommendation tucked away somewhere on a website about flood preparedness or something.

This sort of 'went out' as a thing they were saying to do, and of course was picked up by news and media and repeated.

There's a lot of people thinking "I forgot about that and never did get round to getting those things" along with people hearing it for the first time.

Mix that with "if they're saying it out loud and publicly, maybe it's a bigger issue than we thought".