It's a while since I breastfed, but I think an hour is pushing it, esp as it was quite warm today. I know it's precious stuff, but I would throw it away. If your baby is very young, I would be careful how much/often you express because it can disrupt your supply before the baby is about 6 weeks old. I was a slave to the pump with my first one and had boobs like melons and then quickly dried up. With my second the midwife banned me from pumping for 6 weeks and I fed my son for 10 months.