A placed minecart vanished in spawn-protection area

In spawn-protection area,
1. A Non-opped player tries to place a minecart on rails.
2. Ofcource (really? a boat can be placed) the player cannot, and the minecart does not appear in a world.
3. The minecarts has also vanished from the player inventory!

Actually, it has been only invisible, and so the player can retrieve the minecart by clicking the empty slot.

This is strange behavior, right?