In one of the last proofreadings of FE the A-a octave was preceded with naturals, which are highly unjustified here. The signs were probably added – by Chopin or perhaps by the reviser who worked with him – together with the necessary 
returning a2 on the 12th semiquaver; it is possible that this is the fact that influenced the person introducing the corrections. The naturals are not included in the manuscripts, they were also removed from GE4 (→GE5).
Compare the passage in the sources »
category imprint: Differences between sources
issues: GE revisions, Cautionary accidentals, Authentic corrections of FE
notation: Pitch