Potential Brake Problem?

[CrazyJew89]

Coming back from the store this evening I had something frightening happen on the 535. I went for the brake pedal to start slowing down for a light and it went almost all the way to the floor, before it started to grab. As soon as I let off and went for the pedal again though everything went back to normal, and stayed normal for rest of the drive home. I did not notice the brake light come on if it did or anything else out of the norm. The brake fluid and power brake/steering fluid appear to be at normal levels.

From the bit of reading I have done so far it seems these hydroboost brake systems can do all sorts of strange things, but I did not find anyone describing this or anything similar. Anyone got any thoughts? Is this a sign of something on its way out?

[Kyle in NO]

Master cylinder bypassing fluid internally. Replace it.

[CrazyJew89]

Thanks for the simple answer Kyle. If you don't mind, what makes you so sure that is the issue? Do you know if there are rebuild kits out there or am I out of luck going the rebuild route?