Really? I've been using 0.3.23 for a while and I've had to pay the transaction fee on every single transaction except for about 5/100. For me, the *rare cases* are when it doesn't make me pay a fee. Did something change in 0.3.24?
Care to share an example transaction so we can see why?
I can only guess you're making payments with outputs smaller than 0.01 BTC?
Went to grab some example payments and I noticed a pattern

It seems that in any batch of payments, the first payment I send is free, and any subsequent payments charge the transaction fee.
I guess sending more than one transaction within a short time period requires the fee.
I normally send a few payments at once, as I'm paying out a bunch of members from our site
