I noticed that when I tried to compile in TextMate after installing FB4 it would load the flex-config.xml from the newly installed FB4 instead of my original location.
I've not installed Flash Builder 4 so don't know what it gets up to. From what you've described I can only think that it's been quietly adding the compiler tools to your PATH. Can you open a terminal and enter:
echo $PATH
and let me know what you see. Knowing version of the bundle you're using would also help.
Does anyone have an up-to-date comprehensive setup for using the Flex SDK with TextMate? Everything I found on the web via searches are two to three years old. I believe that I have everything in order but still can't compile.
I don't have a tutorial, but the bundle help doc should suffice - Bundles > ActionScript 3 > Help.
Cheers, Simon