Amaratzus

On Shabbos, I was talking about the kal v'chomer that Rashi notes appears in this parsha, saying it is one of ten that appear in Torah (Tanach).  I commented, I wonder why Rashi first comments about this here, the second time a kal v'chomer appears, when the first one is in parshas Mikeitz.

Then I looked up the first one in Mikeitz and saw that Rashi actually does comment there, the first time a kal v'chomer appears.  That led me to thinking how absurd and embarrassing it is that after decades of reading Rashi, I still don't know the basics, i.e. what Rashi said.  That is amaratzus (being an am ha'aretz, ignoramus).  L'havdil, a medical student has to know far more information than what is contained in Rashi on Chumash, and he studies it and knows it because it's important to get good grades.  What I (we?) do is passively read it without committing it to memory (beyond what we had to study for school decades ago).  So yes, I know many Rashis, but it still surprises me what I don't know.