Just got this notification, but /proc/mdstat looks fine. Might be something to investigate later.
{{{
This is an automatically generated mail message from mdadm
running on ibiblio1.fedoraproject.org

A SparesMissing event had been detected on md device /dev/md3.

Faithfully yours, etc.

P.S. The /proc/mdstat file currently contains the following:

Personalities : [raid1] [raid6] [raid5] [raid4]
md0 : active raid1 sdb1[1] sda1[0]
513984 blocks [2/2] [UU]

md2 : active raid1 sdb3[1] sda3[0]
1020032 blocks [2/2] [UU]

md3 : active raid5 sdf4[5] sde4[4] sdd4[3] sdc4[2] sdb4[1] sda4[0]
2387419200 blocks level 5, 64k chunk, algorithm 2 [6/6] [UUUUUU]

md1 : active raid1 sdb2[1] sda2[0]
9213184 blocks [2/2] [UU]

unused devices: <none>
}}}