Ladies being seated at luncheon

I recently hosted a luncheon for several ladies. When they had gathered at the table I realized they were all standing by their chairs and I didn't know why they didn't go ahead and seat themselves. I invited them to be seated and we had a lovely lunch. My understanding of this rule of etiquette is that younger persons and men would wait for the ladies to be seated but I've never seen older ladies wait to take their seats.

What did I miss?