I have a 2003 SE-L and this happened to me last year...
I noticed the brake warning light came on so rung lexus and they said needs to come in for new pads etc which was due any how. I had to have a curtesy car so waited 10 days for this.
7 days later I was driving up the M1 and the pedal started to go soft then completed went to the floor metal to metal! I managed to stop from 85ish and them limped to the nearest lexus dealer.
I got the car shipped back to my dealer and got a train home (paid for by lexus)!
When I asked they said the pads had warn through and they had replaced the pads and discs now and picked up the car some £400 worse off on the saturday.
Monday I drove up the M1 again and guess what.. same happened! this time I was nearer my main dealer so took it in there and went ape!
I left and went home and later was told it was the brake mast cylinder that was at fault.
I had to wait 4 weeks to get this fixed, got a rx Se to drive mean time but did not get too much else from Lexus so I complained officially.
did not hear anything else so not too impressed...
Just be carefull and get this checked as mine really was 2 near misses at high speed. thank *** for good handling to scream across 3 lanes of traffic to the hard shoulder!
Cheers