Gritty sandy feel in girlfriends vagina?

a girl i am talking to is a very clean respectable girl. i believe she has not had sex with but maybe 1 or 2 or 3 guys (she respects herslef). we are taking things slow but i fingered her vagina and it felt very grittty inside. kinda like sand. i am a college grad and have had lots of experience with girls. i havent felt a private area this "sandy before". she is very tight also, so i know she doesnt have much sex. is there any reason for this? is it becuase she has not had sex in a while so whatever that stuff is all accumulates? help.: