No, it's not a FERPA violation for a student to return graded assignments to classmates. FERPA protects the privacy of student education records. While a graded assignment might be considered part of a student's education record, the act of a student handing another student their own graded paper doesn't constitute a release of protected information by the educational institution. The student who completed the work is essentially choosing to share that information.
FERPA violations involve the *school* improperly disclosing information. A student acting on their own to share their graded work is not a FERPA violation.