[gentoo-user] can't mount ext4 fs as est3 or ext3

I get the following in /var/log/messages

EXT3-fs (sda5): error: couldn't mount because of unsupported optional features (240)
...
EXT4-fs (sda5): couldn't mount as ext2 due to feature incompatibilities
...
EXT4-fs (sda5): mounted filesystem with ordered data mode. Opts: (null)

Here is the entry in fstab

/dev/sda5	    /		ext4	noatime,discard	     0 1

I am having no difficulty, but seeing the first (error) message every
day in logwatch is annoying.

Since all my fs are ext4 I could remove ext3 support from the kernel
(3.5.4).  Is that the recommended procedure?

thanks,
allan