My Aunt Jean used to call my family "The Bickersons" because my sister and I were always at each other and my parents were either mediating or bickering about something else. That isn't to say we didn't have an excellent childhood or that Mom and Dad didn't get along -- my sister and I are buddies and my parents just celebrated their 40th anniversary.
As long as it doesn't veer into resentment or violence, there's nothing wrong with bickering. I'm a big believer in it. It keeps things fresh, it lets people know you know them well enough to push their buttons, and as long as things get resolved and there's no major ongoing problem that makes you hate the other person, it can be a healthy way to exorcise/exercise your agression.
For example: I was asking J what I should write about last night, and to get a prompt reaction, I stuck my finger in her armpit. This led to a poking match, then an elbowing match. Sometimes - and J does this to me also - I'll provoke her just because I'm bored. This probably doesn't qualify as bickering, but I'll let you know how this theory holds up over time.