Hm, I looked at the thoughts through DT and saw this 'Military (unprotected): Was worried not to have adequate protection recently'. It shows for all dwarves which aren't in the 6 dorf squad that I have (in other words, all the civillians) and I haven't seen this thought before. I know it isn't clothes related because I've seen the clothes related ones before.
I suppose they got scared when I had them pasture the 'tamed' invader mounts which turned on them (I was trying to butcher them and had no clue why they no longer showed up in the animals list) and while the crocs did end up killing two haulers, I did have my macedorfs go over to the pasture area to kill the hostile mounts.
Or maybe when I accidentially let a goblin out of the cage (got killed by cage trap and ignored the dwarves) and then I decided to let the other one out just for the heck of it.
Or maybe because a failed mood dwarf (clothier that I didn't want a mood for) went beserk in the bedroom area, although two or three children actually held their own quite well until a macedorf came to the rescue.
OR, it's a subtle hint that I should beef up the military?
Edit: The wiki brings up nothing.
Edit: Oh, it's something the siren script in DF hack uses. nvm then. Source:
http://www.bay12forums.com/smf/index.php?topic=118497.msg3751594#msg3751594