How often do you rebalance your portfolio?

[Pat Southern]

I've never rebalanced my portfolio and due to unequal returns I'm pretty sure I should. The only thing I really know about investing is that I know nothing. With that in mind, over the past 2.5 years I've sporadically thrown my money into 3 vanguard funds: S&P, small cap value and emerging markets (as a tournament player most investments came in large chunks not consistent deposits).

My cost basis for these 3 are about 40%, 40%, 20%(respectively).
My portfolio is now about 35%, 35%, 30%.

My question is is this disparity worth reallocating to my normal investments?