order by for strings

I have two postgres 7.2 servers. One is running 7.2.3 and one is running
7.2.4. I am querying for a word list and doing an order by on the word
field.

On the 7.2.3 server it is ordering like this:

a
A
b
B
c
C

which is what I want. But on the 7.2.4 server it is doing it like this:

A
B
C
a
b
c

Is this a change from 7.2.3 to 7.2.4 or a configure or compile option that I
set differently on the two systems?

Thanks,

rg