It's been nagging me this whole time so I decided to even register on the forum to solve this question.
Everyday I send those free crystals you can send everyday to some of my guild members. But later on, when I try to send gifts to those I forgot to send, I just can't because the "send gifts" button is not there anymore, even though I haven't reached the maximum limit of crystals that can be sent per day (which I believe is 16). Is it normal or is it just me?