Rename Block Bug

I was playing on my survival world, and got the idea to use the new anvils that have been added in 1.4.2, to rename a Jack O' Lantern to "Casper".

• Sometimes i just feel kinda lonely when playing SP, so i renamemed a block, so i could have a portable "friend". and then i placed him next to my craftingtable, and when i picked him up again, his name was reseted, and then was again called Jack O' Lantern. and then i renamed him again, and the same happened, and then at the end, i had wasted alot of levels, because of this Bug. I hope it will be fixed