If you see a message like this in your logs:

ext4 filesystem being mounted at /boot supports timestamps until 2038 (0x7fffffff)

it's an indication that your filesystem is not Y2k38-safe.

You can also check this manually using:

$ tune2fs -l /dev/sda1 | grep "Inode size:"
Inode size:           128

where an inode size of 128 is insufficient beyond 2038 and an inode size of 256 is what you want.

The safest way to change this is to copy the contents of your partition to another ext4 partition:

cp -a /boot /mnt/backup/

and then reformat with the correct inode size:

umount /boot
mkfs.ext4 -I 256 /dev/sda1

before copying everything back:

mount /boot
cp -a /mnt/backup/boot/* /boot/