We all have the tendency to seek out old, past feelings, ways of interacting and so on when embarking on a new romantic relationship. That's just a natural part of being a human being. The problem with this aspect is that it increases the likelihood that that's the underlying appeal to this relationship.
You probably felt comfortable together right from the start -- your bond feels natural, familiar, as if you've been a couple for a long time or even as if you've done it all before, together. But this is far less likely to be two souls from a past life reuniting in this one than it is to be two people reenacting past relationships from this life -- revisiting feelings experienced either with your parents or with significant lovers from your past. Why is that a problem? Because it could mean that your growth is stagnant in this new relationship, if you're just acting out an old one. There isn't room to grow within a relationship unless you're able to truly be yourself as an individual, and to see your lover as their own person as well. Furthermore, you could be reenacting past relationships that weren't good for you the first time around, much less this time. You should both take care to examine your bond closely and make sure that you're interacting as individuals in the present rather than carbon-copy figures from the past.