This sounds like a regular Vaginal orgasm, but it's hard to know without having been there

... Congratulations, your girl's now among the 30% who have experienced this... Good job
The secrete sounds like normal natural lubricant, this is different from woman to woman, but perfectly normal.
Most women do, in my experience, become a little more lubricated right after they come.
What you may want to try is going deep, stimulating the Deep spot, before going to the G-spot.... It helps sometimes.
Every Girl is different, so the times you've been with one is not as important as how much you are actually interested in giving her orgasms..
Trust me, by my 3. girl she told me I was better than anyone she'd had before... I think that demonstrates how much your focus on her counts, and how much bad sex women experience...
Being able to give a girl an orgasm, and being interested in doing so, puts you far above the Average.
Cheers