inconsitent antialiasing

[Juan Lorenzo Rodriguez]

Hello,
        I am running gimp 1.0.4 on red hat 6.2 
I am trying to make text gifs in gimp, and found a strang inconsitency.
If you look at the attached gif, 
the "T" in "TE" "TA" "TH" "TQ" all look different. 
I need a context-independent antialiasing solution.