Placing a Block of Sand at a falling Block of Sand

Dear Mojang,
I think I found another bug in Minecraft.
I don't know if it is intended.

Informations about the bug:

I downloaded the newest snapshot (Minecraft 1.5)
and tested it. While testing i found out that
if you place a block of sand/gravel at the side of a
falling block of sand/gravel , it will appear
one block higher as you placed it. (Photo1_1 & Photo1_2)
This bug sometimes forces the blocks to stuck into other blocks.
(e.g. if you place a block above a falling block of sand)
(Photo2_1 & Photo2_2)

Thank you for your attention.
I hope I dont report a bug you already know.
If it is intended please leave a comment so I can know it.

Greetings, LionKILL
(I'm from Germany please don't wonder about my bad english 😉 )