I have blindly trusted the food served on AA's planes up until now, but I could see where on such a long trip something bad eaten early might cause problems before one lands.
Sorry you went through that and hope it wasn't too severe. OT: my bout with dysentery in Mumbai was horrible, sickest I've ever been. Wouldn't wish that on my worst enemy. It was brought on by carelessness during eating (on a beach, not aboard AA flight).