thunderbird master security device

[Skunk Worx]

Hi!

I use F11 and thunderbird for my email. I haven't yum updated for a few 
weeks and I got around to it last night.

The latest updates gave thunderbird a new look and feel, which is fine.

But t-bird is also prompting me for a master security device password in 
addition to the normal email account passwords. This is definitely new 
and I have never set it nor do I know what it is.

Is this an expected behavior? I am planning on going through the 
preferences to checkout the new stuff later today.

Thanks,
John