Thunderbird 38.5 Auto Updated?

I run a 38.5ver portable app version of Thunderbird.

I've got it customized with a couple of addons, and use it occasionally on multiple computers in an IMAP configuration on all computers.

Works flawlessly.

Today, it seem like it 'updated' something, but when I looked to the changelog for updates, for 38.5 the updates were from 2015. 3 things, two of which was a security fix, and some sort of 256 something compatibility with microsoft.

I've got 'check for updates' turned off. So what happened today?

Why the informing of the update to 38.5 when the only updates seem to be from 2015?

I'm going to run a virus scan and see what is going on, but I'm asking just to double check that I'm not being overly paranoid.