[Do I need toaddress Academic Probation for Final Semester of First Masters (One Class with C), but Completed New Masters Degree with high GPA]

I would like to apply to phd programs this Fall, but I am unsure how much I need to speak to the single semester of academic probation I had at the tail end of my masters in Mechanical Engineering when I got a C in the one class I was taking through distance learning (back in 2005, when distance learning formats where wretched).  Besides that semester, my overall GPA for that degree was 3.3.

In 2017  I completed a second Masters degree in Analytics from the same university (a well-respected engineering school) with no C's and an overall GPA of 3.92.  

When applying for Marketing or Economics phds, do I need to talk about that one semester with a C or is it too long, with another graduate degree that went pretty well?  I don't want to draw attention to it if it's not necessary, but I don't want a black eye on my transcripts that could be a huge disqualifier.  Would appreciate advice.