I am not sure if fenugreek causes contractions. But we add fenugreek with spinach too. We add about 3/4th to 1 spoon of fenugreek everytime with spinach & about 3 spoons of soaked fenugreek for dosa batter while grinding (Indian pancake). Fenugreek is actually a cooling agent and doesn't cause heat to body. but every person is different. If u have been ok using it before pregnancy, u will be ok too during pregnancy.
if you only had a little bit try not to stress too much, i don't think it will do any harm. Its probably just in larger amounts but i wouldn't have any more. As long as you're not experiencing any cramps you'll be just fine