Stats are important part in the database. It helps to get better execution plan for the optimizer. Once we rebuild the index its stats is also updated with rebuild command.

Check the last date for rebuild the index in SQL Server

USE AdventureWorks
GO
SELECT name AS index_name,
STATS_DATE(OBJECT_ID, index_id) AS StatsUpdated
FROM sys.indexes
WHERE OBJECT_ID = OBJECT_ID('HumanResources.Employees')