Speculation:

Randy meets Michael in the water works. He was one of few that was there. I am pretty sure that it was mention that they looked Human and Freshly killed. Randy survived, but was bit by a zombie. The curveball, Randy was a slow turner. Michael had to witness the decay of Randy's humanity and all Michael can do is a deathwatch. Why didn't Michael just kill Randy? Randy saved Michael's life

Many have speculated about waterworks, but where the Hell do I pull out my idea? Michael does say Randy. But on my first listen through Michael's inflection seems to be one of command. Not surprise. Remember, the waterworks was a month ago in WA-Time