Is thread bad for puppies?

I just got a call from my dog walker that somehow my 14 week old pup got into my sewing kit and chewed off a lot of thread. Thankfully he didnt injest needles or anything sharp (it was a very very small sewing kit so I knew exactly how many needles I had in there) but she did warn me that he might get really sick and ingest thread might block his system??? I won't be home for another 5 hours and I'm super worried that I might walk into a home with a very sick dog. My dog walker told me that he's super active and normal and he even peed and pooed after all this. Any ideas or anybody had similar thing happened to them? Help..