from datetime import datetime


def valid_timestamp(timestamp_str):
    """ Validate the timestamp to ensure that it is valid
    timestamp_str format: '2015-08-29T22:22:37Z' """

    #No idea why my time is offset by this amount... server time drift?
    mysterious_delta = 296

    timestamp = datetime.strptime(timestamp_str,"%Y-%m-%dT%H:%M:%SZ")
    dt = datetime.utcnow() - timestamp
    print (dt, dt.seconds)
    return False if dt.seconds-mysterious_delta> 150 else True