BIOS warning after CMOS replacement

I just replaced my CMOS battery in a Win 98 system. I receive a warning during the boot-up process stating, “The disk boot sector needs modified, press ‘Y’ for yes, or any key to cancel”. Regardless of selecting ‘Y’ or ‘cancel’, the Win 98 O/S comes up, with no visible abnormalities. Is this something to be concerned about, and what do I do to fix it?