before b2 in 
By putting the 
before b2 in A (→GE), Chopin probably wanted to draw our attention to an unconventional melodic phrase with the characteristic Lydian fourth. Still, the natural was removed in the proofing of FE (→EE1→EE2), which was evidently motivated by the intention to adhere to ordinary rules governing the use of cautionary accidentals. It is difficult to determine whether the correction was made on Chopin's request. The presence of in EE3 is explained by the fact that the text of GE1 was used for its revision. The same situation occurs in bar 35.
Compare the passage in the sources»
category imprint: Differences between sources
issues: Cautionary accidentals
notation: Pitch