The absence of mordent in As could be considered an inaccuracy related to the sketchy nature of this manuscript, but for the fact that in bar 22 
is not included in the version prepared for print. It could only have been a coincidence – the inaccuracy of As here and, for example, the oversight by the engraver of FE in bar 22 – but Chopin's hesitation cannot be completely ruled out.
Compare the passage in the sources »
category imprint: Differences between sources
issues: Chopin's hesitations
notation: Ornaments