Safety of fsck on mounted filesystem

I know that it's courting disaster to do an fsck on a mounted filesystem and then make corrections to the filesystem (I'm referring to an ext3 filesystem here). But is there any danger in doing an fsck on a mounted filesystem if you don't make any corrections? I thought it was perfectly safe since fsck doesn't modify a filesystem without asking you for confirmation (again, assuming you haven't specified -y or something like that). But I recently had an experience where soon afterwards the filesystem showed evidence of corruption. I'm wondering whether the fsck might have been responsible or whether I should be looking elsewhere. Paul Abrahams