The missing 
indication in FE (→EE1) must be the engraver's oversight. Dynamic gradation is undoubtedly an integral part of the 16-bar section that ends here; as a result, the dynamics of the beginning of its repetition should be tantamount to sotto voce in b. 28. It is also confirmed by 
present in the next bar in FED.
In EE2 the indication was probably repeated after GE. Moving it a quaver earlier was an arbitrary decision; however, it may comply with Chopin's intention, since he would sometimes place markings within the range of their scope, and not at the beginning.
Compare the passage in the sources »
category imprint: Differences between sources
issues: EE revisions, Errors in FE
notation: Verbal indications