SensorHistory data missing most recent half hour

Is it normal that the data from SensorHistory is missing the most recent half hour?  What am I doing wrong?

Here is the code:

        var sensorIter = null;

        if ((Toybox has :SensorHistory) && (Toybox.SensorHistory has :getHeartRateHistory)) {
            sensorIter = Toybox.SensorHistory.getHeartRateHistory({:period => new Time.Duration(Gregorian.SECONDS_PER_HOUR*2)});
        }

        var sample = sensorIter.next();

        while (sample != null) {
            println("Sample: " + getMomentDebugString(sample.when) + " " + sample.data);
            sample = sensorIter.next();
        }

And here is the output.  Notice that the current time is 8:33, yet the most recent history data is from 8:04.  This is on the simulator...

2022-Dec-22 8:33:33> Sample: 2022-Dec-22 8:04:55 80
2022-Dec-22 8:33:33> Sample: 2022-Dec-22 8:03:55 null