Indicator data inconsistent

Hello, I have the following bot (and indicator):

using System;
using System.Linq;
using cAlgo.API;
using cAlgo.API.Indicators;
using cAlgo.API.Internals;
using cAlgo.Indicators;

namespace cAlgo
{
    [Robot(TimeZone = TimeZones.UTC, AccessRights = AccessRights.None)]
    public class BugBot : Robot
    {
        private TestIndicator indicator;

        protected override void OnStart()
        {
            indicator = Indicators.GetIndicator<TestIndicator>();
        }

        protected override void OnBar()
        {
            var thisClose = MarketSeries.Close.LastValue;
            var thisOpenTime = MarketSeries.OpenTime.LastValue;

            Print(string.Format("Robot thisClose:{0}, thisOpenTime:{1}", thisClose, thisOpenTime));

            // This gives the correct number
            //indicator.Calculate(MarketSeries.Close.Count - 1);

            // This gives the incorrect number
            var lastValue = indicator.Result.LastValue;
        }
    }

    public class TestIndicator : Indicator
    {
        [Output("Main")]
        public IndicatorDataSeries Result { get; set; }

        public override void Calculate(int index)
        {
            var thisClose = MarketSeries.Close.LastValue;
            var thisOpenTime = MarketSeries.OpenTime.LastValue;

            Print(string.Format("Indicator thisClose:{0}, thisOpenTime:{1}", thisClose, thisOpenTime));
        }
    }
}

I have run this on GBPJPY 1 hour, and am seeing strange behavior coming from the indicator. The follow is output into the log, with the most recent message at the top of this list, I have labelled the lines a to f:

a 17/08/2013 01:00:00.000 | Indicator thisClose:152.552, thisOpenTime:16/08/2013 5:00:00 PM
b 17/08/2013 01:00:00.000 | Indicator thisClose:152.553, thisOpenTime:16/08/2013 4:00:00 PM
c 17/08/2013 01:00:00.000 | Robot thisClose:152.552, thisOpenTime:16/08/2013 5:00:00 PM
d 17/08/2013 00:00:00.000 | Indicator thisClose:152.534, thisOpenTime:16/08/2013 4:00:00 PM
e 17/08/2013 00:00:00.000 | Indicator thisClose:152.517, thisOpenTime:16/08/2013 3:00:00 PM
f 17/08/2013 00:00:00.000 | Robot thisClose:152.534, thisOpenTime:16/08/2013 4:00:00 PM

At line b, the indicator says the close at 4pm is 152.553, but this is different to lines d and f, which both say the close at 4pm is 152.534. Why is this different?

Thanks,

Chris