Next Tether policy 2136

Hello,

I have my iphone 6s . It was unlocked but now phone cannot accept sim card.Is there any possibility that T-Mobile USA can lock again ?
Here is the detail of GSX checking :

Activation Policy Details Serial Number: C76QK3T2GRY7 Initial Activation Policy ID: 2136 MEID: Activation Policy Description: US T-Mobile Locked Activation Policy IMEI: 355415071795471 Applied Activation Policy ID: 2136 Part Description: iPhone 6s Applied Activation Policy Description: US T-Mobile Locked Activation Policy Product Version: 9.3.4 Next Tether Policy ID: 2136 Last Restore Date: Next Tether Activation Policy Description: US T-Mobile Locked Activation Policy Bluetooth MAC Address: First Unbrick Date: 02/29/16 Last Unbrick Date: Unbricked: Unlocked: true Unlock Date: 05/04/16