Firebug issues on POST forms submit

I really like FireBug. I think it's the best tool for web deveploment in years and it's and amazing contribution to open source code and development. But sometimes it does some really tricky, odd things.

Recently I'd serialized a form with jQuery :

var params = $("commentForm").serialize(); // get a string with form parameters

then I use it in a generic ajax call:

$.ajax(
   method: "POST",
   params: params,
   ....
);

Too normal until debugging the result of the query in Firebug. The server's answer contains the params of the form:

Array(
   id:4893
)

But firebug window shows:

Array(
   id:0
)

Different results. Why? Firebug does not capture Firefox query. Instead of that, it replies the query without the parameters. So it can show wrong results to developers who are debugging their ajax posts.
I have noticed that behavior in Linux and formerly in Windows with different versions of Firebug, so don't trust it!