Because your transaction size was more than 2kb, and it costs 0.0001 / kb rounded up that would be 0.0003 BTC
Your transaction was probably composed of many different inputs.
I figured this was the problem. So inputs accumulate on an address until that address makes a "send" to another address then certain inputs are considered "spent" based on how much I've sent?
How am I supposed to avoid these fees anyway? One of bitcoin's strongest and most advertised features is it's ability to have a secure transaction network with low fees.
I mean all of my inputs are generally >= 0.01 BTC.