Potential .NET x86 JIT issue?

The following code behaves differently when built in Release mode (or Debug with optimizations on) and run without the Visual Studio debugger attached.

It also only seems to replicate if the x86 JITter is used. I have tested this on an x86 machine as well as running in WOW64 on a x64 machine (by setting the Platform target to x86).

I've only tried this with .NET 4.0.

When running outside the debugger in Release I see:

Value is 4

When running inside the debugger the e.Value.Length portion of the WriteLine call throws NullReferenceException, which is what I expected to have happen.

The code:

namespace Test
{
    class UsingReleasable<T>
    {
        public UsingReleasable(T obj)
        {
            m_obj = obj;
        }

        public T Release()
        {
            T tmp = m_obj;
            m_obj = default(T);
            return tmp;
        }

        public T Value
        {
            get { return m_obj; }
        }

        T m_obj;
    }

    class Program
    {
        static void Main(string[] args)
        {
            var e = new UsingReleasable<string>("test");
            e.Release();
            System.Console.WriteLine("Value is {0}", e.Value.Length);
        }
    }
}

My peering at the JIT generated code makes me think it is a bug in that piece, but I wanted to double check here before forwarding this on to MS Connect.