another thought....sometimes a welding code will spell out a minimum fillet weld size....ie. AWS D1.1:2010 calls out a 3/16 fillet as the smallest fillet weld size to be used on structural steel and sometimes the engineer of record will still call for weld sizes smaller than that. Like Gerald said, unless the material is sensitive to overwelding, it is permissible to have an oversize fillet weld as long as the extra weld material doesn't get in the way of something.