[X4U] Time Machine purposely not backing up ~/MobileSync?

[Michael Elliott]

I upgraded my iPhone firmware for the first time since July to the  
newest iteration.  (Had previously Jailbroken the phone so I could  
install 3rd-party apps. )

Restore and Firmware upgrade went smoothly, but it wasn't until  
afterwards that I noticed that I had erased my old Notes on my  
iPhone.  No problem, I thought, I'll go into Time Machine, find where  
Apple stores those Notes, and extract them.

I found through some Googling that you go to ~/Library/Application  
Support/MobileSync/Backups/ to find the appropriate backups, stored  
as .mdbackup files.

Unfortunately, when I check in Time Machine in that directory, the  
MobileSync folder exists only in the most recent, hourly backup of my  
drive.

I can't find any trace of it just a few hours ago, much less a couple  
of weeks ago.

Can anybody else with an iPhone and Time Machine check out their ~/ 
Library/Application Support/    directory to see if MobileSync exists  
there, and if it goes Back In Time?

Michael