I have an oncidium which has a new flower spike about 14 inches tall. The plant is healthy but today I noticed the flower spike (and ONLY the flower spike) has a sticky feeling. I have checked for aphids, but there are absolutely none. Nor do any of my other plants have any pests at all. Is this normal for an Oncidium? I bought the plant last year, but it was already in bloom, so this is the first time it's developed a new flower spike for me.