I would say a little odd if money is not an issue, but I am always careful about that assumption. Even when my husband and I were both working full-time, regular jobs, money was ALWAYS an issue. If people have any kind of "hidden" debt, like student loans, car payments, credit card, etc. that does not always reflect a higher standard of living, they can be especially careful to hide it. (It is nobody's business, after all.)
I grew up buying and living on second-hand things, so as a teenager thought nothing of buying a nice, used stereo for my little sister (she loved it, it never occurred to me that that would be weird), or used books for my mom (I always ask for used books--you can get more!!! and sometimes they are collectible). I would say think away that it is strange, but smile, teach your children to be grateful, and if you can't or won't use something, donate it. There have been plenty of Christmases and birthdays where we have not gotten anyone in extended family anything because it was simply more important to keep our heat on and feed our kids. We're not poor by any definition, but we have no wiggle room with our income, either.
So, feel free to think it is odd, but definitely make sure your children are learning gratitude and not to have specific expectations for gifts.