My throat hurts after having my first singing lesson?

I had my first singing lesson today. I went well and I really enjoyed it, but now my throat kind of hurts. My vocal coach is classicaly trained and very knowledgable about singing, so I know for a fact she's training me properly. Trust me. So I'm wondering is this normal? I'm actually kind of prone to sore throats, so what do you think this is? Is it because my vocal chords are stretching and now they're sore? lol. Or should I worry about it?