That is not out of the ordinary at all. I had a gentleman who bought me several pairs of heels and had them delivered to my home so that I could wear them during our meetings. I loved it!
Like Lexxxy said, sizes are tricky so if you are buying lingerie or outfits, getting her measurements rather than her "size" might be a better bet for getting clothing that fits properly.
I've had outfits bought for me and even though I have many lingerie outfits, many are ill fitting due to my small size.
It's always fun to have new outfits, but you may want to prepare yourself just in case the outfit doesn't fit right or she doesn't pull it off as well as the lingerie store mannequin or lingerie model
It's not strange to get requests and all you have to do is ask her