February 2017 - last edited February 2017
I just made the mission to recruit Mordin, and had 5 Renegade Points in the end of it, without any reason.
I want a Paragon run, and I made all Paragon choices. I saved the Batarian and the two humans, I stopped looters, saved assistant, etc... I made all Paragon quick time events and used persuasion when possible.
Is this a bug? Googling for it, I found other people with same problem.
February 2017
I can remember a few discussions about that, some claimed you get the renegade points if you don't leave immediately to shut down the vents and some if you don't leave immediately after the mission is finished.
I don't know for sure if you can avoid this renegade points, but they don't really make a difference. You will easily get all the Paragon dialogue options even if you catch a few renegade points here and there.