In my personal experience, finding a woman that enjoys sucking a cock and swallowing a load is rare, so in that respect you are lucky she has returned to you.
It wouldn't bother me that she had sucked other cocks in the past. I mean, it wasn't moments ago, she must have brushed her teeth and drank some water since then, right?
Regarding trying to learn other things she did, I would not press the issue, though I understand the curiosity. Maybe after you've been with her in the bedroom a few times you might ask her if there is anything special or different that she would like to do.
Please let us know how this works out.