Why did my dnaLinearFit disappear?

[Seldom]

I put dnaLinearFit.js into the scripts folder last fall, and just got another situation where I needed it, but it was gone from the scripts folder. I replaced it from my downloads, so I've got it now, but was reinstalling it the right thing to do? Where did the first copy go? Has it been deprecated? Or does the update process remove it? I've had at least one update since I installed it in the folder.
 
Thanks in advance. 

[dave_galera]

Have you updated PI since you last used dnaLinearFit in which case it will have disappeared.

[Seldom]

Thanks, I suspected an update might have wiped out some of my customization, but wanted to confirm.