Push notifications stopped working

Lately my push notifications stopped working.
I keep getting the following message : “Payload too large” but the notification length isnt large at all - max 50 chars.

This is my notification object: Am i using valid properties?

	//	Preparing the notification
var notification = JSON.stringify(
      "tokens": regId_list,
        "alert": content,   //	Here is the notification message
         // "collapseKey":"foo",
          "delayWhileIdle": false,
          "priority": 10,  //	This is a high priority message. Will send immidiately.
          "timeToLive": 5, //	This property value must be a duration from 0 to 86,400 seconds (1 day) and it corresponds to the maximum period of time for which GCM will store and try to deliver the message. If this property is not set, it is default to the maximum value. When a TTL is set to 0, GCM will try to deliver the message immediately. If the immediate effort fails, the message will be discarded.
            "date": date,
            "cities" : cities   // 40 chars +-