DC Spur in DAC output
First question is your DAC AC-coupled? In that case, the AC coupling will remove the DC offset caused by your DDS.

Second question, unless your DAC is perfect, your DAC will also have a DC offset. Do you know what's the typical DC offset level of your DAC? Again, if the DC offset caused by your DDS is less than say 10% of the intrinsic DC offset of your DAC, I don't think it's worth it to fix it.

Third question, is the ratio between the sampling frequency and the signal frequency a whole number? If it's an even number, you should not have any DC offset, but if you have an odd number of samples per period, you could get a DC offset, For example, with a ratio of 5 because you might get two round-ups and three round-downs giving your a negative DC offset. 

Here's what you could try:


change the signal frequency so that the ratio between fs and f is not a whole number.
Try to add phase dithering, this could remove your DC "spur"