Glad he is doing ok, plants in the lily family contain calcium oxalate crystals which can cause severe acute irritation of the mouth, throat and gut. But longer term, this is a big cause of kidney issues and stones, so try to feed extra watery veg and syringe some water, also cut out any high calcium foods for a couple of weeks (pellets, broccolli, parsley, spinach etc) to give the kidneys a proper flush through and give him chance to eliminate the calcium.
Hopefully a tiny amount is fine if he didnt exhibit any acute symptoms, but... if it was my piggy I would be feeding cucumbers in abundance for a while and restricting many other foods for a good kidney flush just to make sure!