Ok, solved it. There was a problem with the bind pose in maya.
Here are the steps I used to correct the problem:
-Open the outliner
-On the outliner, upwards, uncheck Display>Show DAG Objects only.
-Look for the bindpose, in my case it was “bindpose1”.
-Delete it (may be more than one).
-Export.
This did it for me.
It doesn´t seem that I had more than one bindpose, but still it brought some strange problem.
Thanks KrunkFu for the help.