Just recently did bloodwork test for gliadin ab, siga it it came in high at 56. i have been gluten free for 4 years. what else would cause that?

Nothing. It stays +: You did not mention if you are having any symptoms or what was the reason for doing the blood test. Your immune antibodies against the components of gluten will stay positive if your immune system considers it relevant. Just continue to strictly avoid eating anything with gluten. Keep in mind that even some medications contain gluten. No need to keep testing if the diagnosis is made.