In the store, tap on "Downloads and Updates".
Wait for a little bit and you should see the list of apps appear, with the latest update at the top. If you don't remember updating any apps manually, then they must have been updated in the background.
Bear in mind, this is relevant for Windows Insider Fast Ring. If you don't have the latest version of the Windows Store, you might not see this.
Latest version of the store app is 11605.1000.113.0 (at least on my device).