My guess is that a hydraulic line got a pinhole in it and the hydraulic fluid (called Skydraul) came out in a mist. The stuff will burn your skin and choke you and even peel paint. The reason they use it is because it isn't as flammable as standard hydraulic fluid.
Could someone link to the thread "Terror in The Skies,Again ?". It was posted by big gray tabby on 7/15/2004 @ 1:12:48 PM. It is a frightening account of a flight from Detroit to LA. 14 Muslims were extremely suspicious passengers. Possibly a trial run on how to assemble terrorist equipment while plane is in flight.
It could have been a combo of starved, weary, overcrowded passengers, broken to tears by the sounds and smell of the baby one seat forward, suddenly and rudely awoken from a much deserved sexual reverie by a frustrated comedian-singer turned SW steward or stewardess belting out their inaugaural debut, (which sounds Exactly like the one you heard on the way to Houston Hobby).
So, did they ever say what the problem was?