I put together a new engine and i noticed some oil on the corner of where the block and the head meet and i also saw a couple of drops of anti-freeze in my oil pan when i dropped it...should i re-torque it? Are you supposed to?

 

if you found coolant in the oil then it may be a bit too late.

 

Good chance if you already found it's mixed. You COULD try just draining all the oil, making sure the gasket is not damaged, then re-seal and re-torque but it probably already destroyed it again.