fill-paragraph question

[Elena Zannoni]

Hi, I am using GNU Emacs 21.2.1. I have the variables
sentence-end and sentence-end-double-space
set to the defaults:

"[.?!][]\"')}]*\\($\\| $\\|     \\|  \\)[       \n]*"
and 
t

When I execute a fill paragraph command on the following:

Aaaa aaa aaaaa aaaa, aaaa. Aaaaaa aaaa aaaa. Aa
aaa aaa aaaaaaaaa aaa a, aaaaa. A aaaaa aaaaa.
Aaaaa.

I get the below.  Note that only the end of sentence that was before a
newline became double spaced.

Aaaa aaa aaaaa aaaa, aaaa. Aaaaaa aaaa aaaa. Aa aaa aaa aaaaaaaaa aaa
a, aaaaa. A aaaaa aaaaa.  Aaaaa.


Is this ok behavior? I.e. if I don't explicitly type the two spaces at
the end of the sentences, is fill-paragraph expected to insert them?
Is there any way to make this happen?

I tried to change the value of sentence-end to include one single
space after the period, and left the sentence-end-double-space set to
t, but it didn't help.

thanks
Elena Zannoni