Looks like Sig has been making slight changes to the P365 during production. Check out the thread. Great info.
http://sigtalk.com/p250-p320-p365-p320-x-5-pistols/317980-rolling-changes-p365.html
http://sigtalk.com/p250-p320-p365-p320-x-5-pistols/317980-rolling-changes-p365.html