This isn't my first replay of FF7 obviously, but I guess I never ever paid attention properly to this part.
When Cloud is talking about his first mission with Sephiroth, the mako reactor in Nibleheim. He visits his mother who says
"Let me get a good look at you."
"Is this a Soldier uniform then?"
Cloud then says "Mom...I" and then there is a memory skip, that flash of white thing. I guess I just now noticed that this scene he confesses to his mother he never made it into Soldier and what she thinks is the Soldier uniform is just the average Shinra grunt uniform he's wearing.
There are a LOT of memory skips when he talks to his mother. Obviously he forces himself not to remember them because she would be talking about events in his own life, not his Zack persona.