No, doesn't bother me in the slightest, and I wouldn't ask her how many partners she had in the past. The past is the past, what matters is the now and the future.
Still, if you want it all to end in tears, obsessing about her past is one way to go about it. Most men are not amazing lovers, but if you concentrate on doing your level best to make sure she enjoys the sex, she will think you are great and won't be making any unfavourable comparisons with previous partners. Or, you can keep feeding your obsession and enjoy the train wreck when it happens.