Cat and Lilies! HELP!!!

I woke up this afternoon to hear my ten month old cat, Castiel, vomiting. I thought he might have eaten something funny and was worried about worms (even though he is an indoor cat and has no exposure to such things) and found he had eaten a lily petal. I had no clue where he could have gotten into such a thing but when i went into the kitchen i found my mother had just purchased an arrangement of lilies and flipped my lid.

Needless to say, i threw the lilies away and got my mom to call the vet.

The vet said to give him some food and milk but if it was just one petal and he didnt seem to digest it much, he should be fine. He said call him if there is any problems and didnt schedule any appointment. I gave Castiel some turkey, dipping it in the milk since i knew he would never drink the milk on his own. (he has never been a fan of the stuff).

Its been three hours and i know that the symptoms of an upset stomach (drooling, loss of apatite, retching, lethargy, etc) are the first to show and later come the symptoms of kidney failure. Its been three hours since he vomited and he has been eating fine and drinking well. He even played with my yorkie and isnt acting strange at all, just his goofy self running around my room in a frenzy with no signs of an upset stomach at all.

But i'm really worried! i know its best to take them in within 18 hours but i also know that it takes a few hours for blood tests to show if his kidneys are reacting to the poison and my vet who has always been such a great vet to all three of my pets (and recognized as one of the best vets in our area). The vet still seems so unconcerned! What do i do? He's my baby and i am so worried about him. Any advice is welcome, please!

I'm a worry wart, and, based on this article, I'd take him to the vet.

Or at the very least, have an emergency/24-hour vet on speed dial and know exactly how to get there.

Thanks so much. I called the vet again (my vets clinic is a normal one and the one right next door is an emergency clinic) and the vet said that the treatment he would administer would mostly be fluids (to keep him from being dehydrated if he was refusing food/water) and trying to get the lily petal out of Cas's system (something Castiel seemed to do for himself).

 He also said Cas, since he is a smaller cat, would've shown clear symptoms within two hours, so it looks like i might've dodged a bullet :3

I'm still keeping a close eye on my baby though and it goes without saying there will be absolutely no more lilies in this household.

Thanks so much for the help.

Yeah, it's just not worth it.

BTW:  if your cat wants to chew a plant, there are some ornamental grasses that are reasonably safe, like Zebra.  It's long and flexible enough that I use it as a toy:  I wiggle it on the carpet and Ritz thinks it's a mouse or a snake and she runs after it.  Best thing is, since it is edible, she can 'kill' it. 

In the interest of full disclosure:  use in moderation, and monitor how your cat reacts to chewing something like grass.  Some grasses have 'barbs' on the edges, and some cat grass encourages cats to vomit.  Ritz doesn't have a problem with ornamental grasses, and I never leave it out when I'm not home.  On the other hand, while she loves cat grass (which you can grow yourself in a small pot), it sometimes makes her throw up.