Hey ACarrier,
Is this happening with every dimension you create? Or just sometimes? Sometimes when creating a dimension in Catia it will automatically do what they call a "Half Dimension" for whatever reason. You can get around it by:
After clicking what you want to dimension, right click BEFORE you click the location of the dimension. In the drop down menu you'll see "Half Dimension". Click that and it should return to normal.
If it happens all the time, then you must have a setting or something changed somewhere. Hope that helps!
Ben