Hello, I have not experienced a CS, but after birth your oestrogen levels are very very low (even more so if you are breastfeeding), and this can cause the vaginal tissues to become dry, thin, and brittle (ie yes they can actually graze). The remedy for this - other than using a good lubricant - is to see your Dr for some vaginal oestrogen - either a cream or pill, which delivers oestrogen right where it's needed.