Are gel nails supposed to burn?

So, I got a gel refill and two totally new gel nails (they had fallen out) and when I put them under the UV light (so they could cure and harden) they burned really bad for about 10 sec especially the newly put on gel nails. I'm not sure how to explain it. It felt like hot metal melting into my skin. They're fine now but I was just wondering if that's normal. It happened the last time I went to that salon as well.