What does it mean to have a slightly curved cervix?

Probably nothing. The uterus is composed of muscle and collagen, both are somewhat flexible. The uterus is attached inside you, but is still a bit mobile, while the cervix is somewhat fixed in place by it's attachment to the vagina. When the uterus leans forward or back (or side), then the cervix will be curved a bit. Essentially, whatever the position of the uterus and cervix inside you, it is normal for you.