It is possible for ghsv1 to be transmitted from genitals to genitals, but it's not likely. It doesn't recur that often, and doesn't shed that often, so transmission is far less likely to occur that way. People with ghsv1 just aren't likely to transmit it.
If someone thinks they have ghsv1, they need to get any blisters cultured and typed. They can also do a type specific IgG blood test, but that won't show the location of the infection - whether it's oral or genital.
Since so many people already have hsv1, timing of the testing matters for hsv1. If you had sex with someone with ghsv1 yesterday, get a type specific IgG blood test as soon as possible. If it's positive, it's a pre-existing hsv1 infection. If it's negative now, and positive later, then that's a new infection. It can take up to 4 months to show positive on a blood test, though most will by 6 weeks. The soonest is about 3 weeks.
At least half the adult population already has hsv1 (goes up to 80% or so as you get older), and 90% of them don't ever get a cold sore, so testing is important.
But really - if all you did was have sex with someone with ghsv1, I wouldn't worry about transmission of that at all.