I don't remember being "advised" to do this. I remember a lot of panicky people doing it. Anyway, people who did this (mostly back in late 2001 as I recall) were worried about terrorism.
The connection between this point of yours about terrorism warnings/fears, and Bush's stance on the nation-state of Iraq, truly escapes me.
I think a lot of people had the impression of a pretty imminient domestic threat even if the word 'imminent' can't be found by a Lexus/Nexus search.
That's their problem.
I've got news for you: had there been an imminent domestic threat, Bush wouldn't have sat around for six damn months engaging in a public, meandering debate (first in Congress, then in the UN, always in the media...) over the matter. He would have JUST ATTACKED.
Presidents can do that, you know. They can JUST ATTACK if a threat really is "imminent". They don't NEED to ask for Congressional resolutions or such niceties when a threat really is "imminent". Thus, the fact that Bush didn't do that is one indication that he didn't think the threat was "imminent".
"Imminent threats" don't usually sit there on Pause for six months while you have a heated, public debate over whether to attack them.