.NET client - Failed to obtain socket from pool

hi,

i have a .NET client 1.1.6 running against couchbase server 1.8.1.
It sometimes happens that when i try to remove item from server like
var result = Client.ExecuteRemove(lockName);
while(!result.Success)
{
// log error
_logger.Error(string.Format("Attempt {0} to remove {1} failed. Message = {2}. Exception = {3}. InnerResult.Message = {4}. StatusCode = {5}.",
attemptCount,
lockName,
result.Message,
result.Exception,
result.InnerResult.Message,
result.StatusCode));
}

i see following message to be logged " Message = Failed to remove item, see InnerResult or StatusCode for details. Exception = . InnerResult.Message = Failed to obtain socket from pool. StatusCode = . "

when i check the time then i see it happens just during certain period lasting exactly 10 seconds. so this call will be in the while loop for 10 secs.
what is the reason for this behavior? is there a way to tune it somehow? where does it come from - client or server ?

thanks
Lubos