Would you find this rude?

No I wouldn’t think it was rude.

Sometimes people get busy and it slips their minds to reply.
I wouldn't sweat it.

I often don't get responses to texts or don't respond either.. 🤷‍♀️

No. I don't expect replies to thank me for kindnesses.

It might have been nice of them to respond. But, it depends on how many such messages you might send. Also, it is a 'closed' message, not actually requiring an answer. So I would chill on this.

Did she see the text?

Not if they are on vacation!

I wouldn't stress about it

No.