Could be something you ate, could just be an 'off' day for him.

Poos are different between bub to bub and day to day and not the most reliable indicator of something going on. If you feel he is otherwise happy and alert and is having plenty of wet and dirty nappies I would say hold your nose and wait until tomorrow!

PS Wait until he starts eating food and you'll be wishing for his 'smelly' bf poos!