Spindle Oscillating Movement

Hey all - I have recently built my X-Carve and it has been great thus far! Apart from breaking my bits here and there due to small user errors, I have been extremely pleased with it thus far and have made several carves with detailed text using a 1/16th fishtail bit from my starter kit.

However, when I turn on my spindle to begin each carve, I can’t help but notice there is a slight oscillation in my router - the bit moves ever so slightly in a ellipse, and when it touches my material it usually becomes more rigid, but at times I see small imperfections in text that is carved into the plywood material I have been using. My bolted connections are all tight and the Z axis is calibrated correctly, I was just wondering if there was anything I can do to correct this, or if this is a normal function for the X-Carve.

Thank you all in advance! Happy carving.