Cat ate strip of plastic! Another week, another panic for the cat mama.

SO my little 8lb cat ate a strip of a plastic wrapper. I had a crystal lite container and you know how it has the little strip that wraps around the lid of the canister and you pull it off so you can lift off the lid and get to the individual packets? I pulled it off, it didn't ALL come off but it was like 6 inches by half a centimeter wide and is flat obviously. I put it down on my dresser and when I went to throw it away, she had it and ran off with it. She ran under the bed where I couldn't reach her and I'm 99% sure she ate it. I swept everything, I scooted the bed this way and that way and looked with a flashlight, I sifted through the litter box in case she buried it, checked her kennel and her bed in case she left it there or tucked it under for later, checked under my shelves. It was gone. She ate it. She barfed a little bit, like the size of a half dollar and then that made me REALLY worried. She's never thrown up, ever. She still wanted to eat dinner after, she still drank water, and she still hopped around a bit. I gave her some hair ball gel and she didn't throw up after dinner. Since she only threw up a little before dinner I thought maybe she was just irritated and wanted to get it out of her tummy and not that it's blocking her intestines or anything. I know our dog will eat random things and then throw them up a few hours later. It's been a few hours and the only thing weird is that she's put herself to bed in her crate and i don't know if that's because it's cold tonight or if she's not feeling well. 

My plan is that if she throws up again, I take her straight to the vet. Is that safe enough of a plan? Just watch her, check her poo, and wait and act if she throws up. From my understanding, the vet would do an x-ray and then advise watch and wait, but since it's plastic and thin, it probably wouldn't show and then they'd want to do another X-ray in 48 hours. My husband was like ... she probably eats a lot of stuff we don't know about and nothing has happened before so told me not to worry, but I just feel worried anyway. 

I'm sure you are aware that this is what you are told to look out for when a cat has ingested something:

Drooling, vomiting, diarrhea, abdominal pain, lack of appetite, straining to defecate; constipation, lethargy or biting or hissing when picked up. 
 

I understand it will take around 10-24 hours for stuff to pass through a cat's digestive system.

I would phone my vet and explain the situation then I'd take her advice as to whether I should bring my cat in or keep her comfortable and watch her closely.

It's been about 15 hours. She's acting normal. Harassing me by zipping all over the room and begging for food. Our vet isn't open but I'll be sure to call.