Why do I get for months December, January, February when I am expecting January, February, March

Why do I get December, January, February for the timestamp when I submit https://api.enterprise.apigee.com/v1/o/arity-ccp-nonprod/environments/dev/stats/developer_app?select=sum(message_count)&timeRange=01%2F10%2F2017+00%3A00%3A00~03%2F31%2F2017+23%3A59%3A59&timeUnit=month

abreviated response is :

{

“environments” : [ {

“dimensions” : [ {

“metrics” : [ {

“name” : “sum(message_count)”,

“values” : [ {

“timestamp” : 1488326400000,

“value” : “3.0”

}, {

“timestamp” : 1485907200000,

“value” : “59.0”

}, {

“timestamp” : 1483228800000,

“value” : “0.0”

} ]

} ],

“name” : “Aleksandr-HERE”

}

Hi, these timestamps are in UTC. When i converted your times, they show as Jan1, Feb 1, Mar 1 UTC