What is the alignment of the structure being copied? For structures which contain only scalar members, this is the same as the size of the largest scalar. If the structure contains other structures, then you have to apply this rule recursively. And the alignment of the parent structure is max(parent structure, child structure). (There might be some exceptions to this, but I can't think of any.)
I suspect the alignment the structure being copied is more than 4, which makes the 4-byte alignment, and the 4-byte aligned destination address (it ends with 0xC) both suspicious.
Thanks and regards,
-George