[15.00.670.4000] [PS] [C#] [Windows]: PowerShell Runspace to Exchange Online Budget Exceeded Error

I tried with runspace.Close and runspace.Dispose, but it has no effect. 
From the message bellow, I see there is a maximum of 5 runspaces in 60 sec period, but with my code I am closing and disposing runspaces and that limit shouldn't be and issue. Of course, there is always a chance that I am doing something wrong.


message (some text is masked with dots):


   

       Connecting to remote server failed with the following error message : Fail to create runspace because you have exceeded your budget to create runspace. Please wait for 45 seconds.
    Policy: CN=GlobalThrottlingPolicy_....,CN=Global Settings,CN=ExchangeLabs,CN=Microsoft Exchange,CN=Services,CN=Configuration,DC=namprd05,DC=prod,DC=outlook,DC=com; 
    Snapshot: Owner:	Sid~NAMPR05A001\.......~WSMan~false
    BudgetType:	WSMan
    ActiveRunspaces:	0/3
    Balance:	600000/1800000/-3000000
    PowerShellCmdlets199/200
    ExchangeCmdlets9223372036854775807/Unlimited
    CmdletTimePeriod:	5
    DestructiveCmdlets60/Unlimited
    DestructiveCmdletTimePeriod:	Unlimited
    QueueDepth:	Unlimited
    MaxRunspaces:	5
    MaxRunspacesTimePeriod:	60
    LastTimeFrameUpdate:	4/23/2013 8:48:20 PM
    LastTimeFrameUpdateDestructiveCmdlets:	4/23/2013 8:40:36 PM
    LastTimeFrameUpdateMaxRunspaces:	4/23/2013 8:48:08 PM
    Locked:	False
    LockRemaining:	00:00:00 For more information, see the about_Remote_Troubleshooting Help topic

Here is the simplified code (actual is more complex, but basically this is it):

    private Collection<PSObject> GetUser(string userName, string password)
    {
        try
        {
            serverName = "https://outlook.office365.com/powershell-LiveID?PSVersion=2.0"
            SecureString pass = new SecureString();
            foreach (char x in password.ToCharArray())
            {
                pass.AppendChar(x);
            }
            WSManConnectionInfo connectionInfo = new WSManConnectionInfo(
                new Uri(serverName), PSNamespace, new PSCredential(userName, pass));
            connectionInfo.AuthenticationMechanism = AuthenticationMechanism.Basic;
            connectionInfo.SkipCNCheck = true;
            connectionInfo.SkipCACheck = true;
            CallContext.SetData("WSManConnectionInfo", connectionInfo);
            using (Runspace runspace = RunspaceFactory.CreateRunspace(connectionInfo))
            {
                using (PowerShell powershell = PowerShell.Create())
                {
                    try
                    {
                        powershell.AddCommand("Get-User");
                        powershell.AddArgument(userName);
                        runspace.Open();
                        powershell.Runspace = runspace;
                        return powershell.Invoke();
                    }
                    catch (Exception e)
                    {
                        return null;
                    }
                    finally
                    {
                        runspace.Close();
                        runspace.Dispose();
                    }
                }
            }
        }
        catch (Exception e)
        {


            return null;
        }
    }

Thanks,

Boris