Welcome to the board!
The thing you need to keep in mind is that although we talk about a quarter inch seam, you don't measure the seam, you measure the resultant patch. Here's how to check:
Achieving an Accurate 1/4" Seam Allowance
Fabric and thread thickness can affect needle placement. I often double check at the beginning of a project to make sure that my needle position is correct for that fabric/thread combo. I have a Viking, use the metal foot with a flange and usually have to move the needle to the right, usually at the 1.8 or 2.0 position.