to think if someone's been your bridesmaid, they should ask you to be thiers?

[winkle2]

I went to a hen do recently and the bride-to-be has been bridesmaid 5 times yet she was only having 2 bridesmaids herself.

Is there some sort of wedding etiquette?!

All the people she'd been bridesmaid for were at her hen party which I thought might have been a bit awkward.

Why? Weddings are enough of a minefield without the need to be forced into having multiple bridesmaids for no better reason than you'd been a bridesmaid at their wedding.