Is it an expected behavior that after reorg SALES DATA index is changed?

We have recently performed reorg.

By below query we determined the reorg factor:

SELECT ui.index_name,trunc((ut.num_rows/ui.clustering_factor)/(ut.num_rows/ut.blocks),2)

FROM user_indexes ui, user_tables ut, user_constraints uc

WHERE ui.table_name=ut.table_name

AND ut.table_name=uc.table_name

AND ui.index_name=uc.index_name

AND UC.CONSTRAINT_TYPE='P'

AND ut.table_name=upper('SALES_DATA');

The query used to return "SALES_DATA_PK" as "index_name before reorg. Now, it shows "SALES_DATA_QTY_FORM_121_FI". Is it an expected behavior. anyone can help explaining why the index name has changed after reorg?