iPod touch Very strange - Some numbers not shown in album titles [SOLVED]

I have 13 albums of an artist.
In iTunes 10.6.3 I put the dates released at the start of most of the albums. Some are compilation albums - so no date.
iTunes sorts these into date order:
Anthology
Great Moments with Pharoah Sanders
The Impulse Story
1971 Black Unity
1971 Live at the East
1971-73 Village of the Pharoahs
1972 Wisdom Through Music
1980 Journey to the One
1982 Heart is a Melody
1987 A Prayer Before Dawn
1987 Africa
1989 Moon Child
1992 Crescent with Love

I have synced these to my iPod Touch (5.1.1) but only some of the dates are shown:
Anthology
Great Moments with Pharoah Sanders
The Impulse Story
Black Unity
Live at the East
1971-73 Village of the Pharoahs
1972 Wisdom Through Music
Journey to the One
Heart is a Melody
1987 A Prayer Before Dawn
Africa
1989 Moon Child
Crescent with Love


I tried copying the album names from iTunes and pasting them into Pages to display the invisibles e.g spaces. There seems to be no difference between them - just one space between the date and the rest of the title, and no spaces spaces at the start.

Any ideas what's causing this?
Thanks for your help.

More info:

When the iPod is attached to the computer, all the dates are displayed correctly in iTunes/DEVICES/Music.

SOLVED - Not sure exactly why.

I deleted one title - 1992 Crescent with Love, and retyped it.
I then resynced my iPod.

All the album titles are now displayed correctly.
Very strange!