I've only experienced with an online tree - I have not yet tested from FTM.
It appears to happen every time if someone does not yet have a date of death.
Has happened saving a FindAGrave link, an SSDI, a Public Record for someone still living.
At first I thought it was the 100-year rule that was impacting, but earlier today I got hit on someone who was born in July 1912.
I'll test with IE 10 and a couple of other browsers and let you know if it is the same.
Edit - It happens with IE 10 and Google Chrome 26 and Opera 12.
It does not appear to happen using FTM 2012.