BotBuilder-MicrosoftTeams: MS bot with Ms teams channel gives 400 error

I have V3 BOT with Microsoft teams channel. I see following sporadic issue where it seems like teams is failing send response back to bot via serviceURL

Error: POST to 'https://smba.trafficmanager.net/amer-client-ss.msg/v3/conversations/a%3A1qNZgTUu4ASGZkGKPYDtZque7ucUYmAuWHi7pVx2qfw7gtuHtEUybWEJnQDeZl31zAcglGMyoxKUik-VOpLKqGXop4UFTiQ70NZzkj49LHhNSeVlYFnJTCAjVVFtoViDt/activities/1529002753254' failed: [400] Bad Request
    at Request._callback (D:\home\site\wwwroot\node_modules\botbuilder\lib\bots\ChatConnector.js:559:46)
    at Request.self.callback (D:\home\site\wwwroot\node_modules\request\request.js:186:22)
    at emitTwo (events.js:126:13)
    at Request.emit (events.js:214:7)
    at Request.<anonymous> (D:\home\site\wwwroot\node_modules\request\request.js:1163:10)
    at emitOne (events.js:116:13)
    at Request.emit (events.js:211:7)
    at IncomingMessage.<anonymous> (D:\home\site\wwwroot\node_modules\request\request.js:1085:12)
    at Object.onceWrapper (events.js:313:30)
    at emitNone (events.js:111:20)
    at IncomingMessage.emit (events.js:208:7)
    at endReadableNT (_stream_readable.js:1055:12)
    at _combinedTickCallback (internal/process/next_tick.js:138:11)
    at process._tickDomainCallback (internal/process/next_tick.js:218:9)
``