It's not an age limit per se; it is more of an age statistic where the probability of being sexually active, and thus already being infected, is so high for the over 26 cohort that the vaccine (and hence the cost to the health care system) would be wasted. It is estimated that 80% of the population has population has been exposed to HPV.
Yeah, I know the exposure figure is high (hence the offhand joke in another thread somewhere) but exposure doesn't equal contagion, necessarily. My own experience points to one of three things. Either I didn't get it, or I got it and I'm not a vector, or I got it and nobody ever said anything (seems improbable since I've always been vocal about it).
That said, I'm way past the age limit too. But never really considered if it was an option, as I'd been exposed already. Of course, very unlike me, I did not have this conversation with my doctor. With an upcoming physical, perhaps I will.