Could be an infection, or a minor STD
What can cause abnormal vaginal discharge
Possible Vaginal Infections from WebMD
.
What's Normal in Vaginal Discharge
She will know her body better than anyone, however if she is experiencing something different than usual, rather than panic and think the worst, it's best to get herself (and you) checked out
This is a rather indelicate question, but is there any odor?