Does it pose a specific problem? You're both adults. If your relationship isn't hurting anyone and if it's healthy, then there's nothing to worry about. The number is irrelevant in the grand scheme of things and if it all works out for you both, a couple of decades or so, the gap won't even be apparent. Now, if you just want advice on how to handle it, being the older party, then mainly it would have to be - "Don't use your seniority to control her or the relationship," because what really makes or breaks that kind of relationship isn't age, it's power dynamics. Treat her like an equal and you're good.