I have an issue I haven't had much luck tracking down. When I'm stopped/stationary, if I push on the brake pedal (engine running) I can feel a bit of a 'step' or 'pop' in the pedal right near the end of the pedal travel. I can also hear a creaking noise coming from somewhere under the car. I can't tell if its from the front or back.

All 3 brake hoses seem OK, no bulging or cracking. No leaks anywhere in the system as far as I can tell, fluid looks normal and full in the reservior. Brake discs look somewhat worn, but not 'used up' and the brake pads are not worn to the squealers yet. They seem to act normal - same pedal feel as before (aside from the 'pop'), and it doesn't seem to pull to one side or the other.

This only started up in the last week or so, and its bugging me. Anyone had this happen before? Anything I could check? This is my DD, so anything helpful is good.

(Discs at all 4 corners BTW)