Found a wild stat about JFK files that made me second guess everything

Was digging through the National Archives online portal last night, just browsing the declassified JFK collection out of curiosity. Found one FBI memo from 1963 where they mentioned tracking Oswald for weeks before Dallas, but the timeline in that memo contradicts the official Warren Report by like 11 days. The memo is dated October 11th and says surveillance started September 30th, but the report claims no active tracking until November. I know these records are messy and redacted, but that specific gap bugs me. Has anyone else cross checked the raw documents against the final conclusions, or is this just normal bureaucratic sloppiness?