it is normal. it could be that she was extra-excited. also during different periods in her cycle, her natural vaginal lubrication can do things like get really clear or whiter looking, also she can be more "wet" sometimes during her cycle than others...etc.
now, it is also possible that she has a yeast infection or something of that sort...so if there is itching, smell, etc. involved along with this white substance, then she needs to get that taken care of.
probably what you saw however was just an extra-excited vagina at just the right time in her cycle to have a white-ish discharge.
my guess is no-biggie. i hope that you two losing your virginities was a great experience and that both of you had a really good time.
jasmine