Our little team at work (6 people) is doing a Secret Santa...names drawn a few weeks ago, limit of £5 set. All very good natured and nice so far.
However, we're supposed to be exchanging today and one person has just announced "oh, I won't be opening mine today. I'm going to keep it until Christmas Day. And X and Y are doing the same too" 
AIBU to think that this is just not how you do things? Secret Santa gifts are supposed to be opened when you get them, right? Part of the fun is seeing who gets what and trying to guess your Santa etc. It loses so much if you keep it until Christmas Day 