FACL, lost in it's behavior..

Hi,

I got FileA that have 640 a getfacl FileA give me

# file: FileA
# owner: me
# group: me
user::rw-
user:aUser:r--
group::r-x			#effective:r--
mask::r--
other::---

So it's give me the expected...

but when I do

chmod 600 aFile
getfacl aFile

...
user:aUser:r--		#effective:---
...
mask::---
...

Why suddenly aUser lost his ability to read the file !?!?!