Stepping on seagulls???? [brakes]

This past week I've gotten a strange sound when pressing the brake pedal. It sounds like something pneumatic, the best of which I can only describe as slowly stepping on a seagull. There has been no change in pedal feel or brake function. I couldn't exactly pin-point its origin, but it is definitely coming from somewhere in the interior, and could be anywhere in my footwell between the pedal and to within the transmission hump. I think I may have seen some sort of black tubing there under the plastic. My only other answer could be something needs lubricating, but it doesn't quite sound that simple. Anyone ever see/hear of anything like this before???

Wouldn't ya know, it must have been a fluke.... I feel like the boy who cried wolf; it's like every time I post a thread it turns into a false alarm!?!?! The sound was gone this morning. Maybe it had something to do with the warmer weather or higher humidity we had last week. I guess no one had an answer anyway, but if it happens again I'll let you know and put up any fix I come by. This must be the good-luck forum!!! Make a thread, and and your problems disappear!!!
Cheers!