Uncorrectable data error reading ...

[Michael Richard <richar01_(_at_)_gel_(_dot_)_ulaval_(_dot_)_ca>]

I woke up this morning with a screen fully filled with that text, written on a beautiful white on blue:

wd0a: uncorrectable data error reading fsbn 3874778 (wd0 bn 3874841; cn 961 tn 1 sn 26), retrying

I rebooted with a floppy disk to do a fsck (-f because the system was marked clean) and it deleted one useless file using that sector.  I did a second fsck and the only error I got was:

CANNOT READ: BLK 3874736

and the same "white on blue" error than above, repeated a lot of time.

So I assume that this is my first bad sector (on this disk).  Am I right?
If so, is this possible to tell to OpenBSD to not use this sector anymore?

Michael