Yes, that is what I thought too. But I used the "-f dat" option while recording, which according to arecord's manpage should have given me 48000 Hz sampling rate. Based on this, I had converted au->flac by specifying 48KHz sampling rate.

In audacity I had to reduce the speed (Effects menu) by around 8% to make the audio replay properly ... this corresponds to 44.1 KHz. (If I forced audacity to 44.1 KHz from its GUI (lower left), it wouldn't play the track at all)

So the "-f dat" option of arecord actually recorded at 44.1 KHz and not at 48 KHz !?
Here is the exact command that I used:
$> arecord -D plug:hw:1 --duration=6300 --file-type au  --format=dat --nonblock `date +%Y%m%d%H%m%S`.au


thanks,
->HS