I have the same machine and it did the same once.
I rethreaded and it works like a charm

I have a Brother machine as well, not this one that you have and I couldn't find anything about oiling it so I called Brother and they told me that I would have to take it in to the service center to have it done at least once ever 6 months if I did alot of sewing and if didn't do a lot of sewing then I would need to take it in about once a year. They have a service center there in Fort Worth the address is Sewing World, Inc, 6958 Green Oaks Blvd, 817-263-0572. I hope this helps you. This is the first machine that I have that I couldn't oil myself.

Sounds like the "blind Stitch" setting.

actually my (same) machine does the same thing with the walking foot. figured I might have ruined it somehow

I have this machine and have used it pretty hard for 26 months.
It is great.
I use it to sew jeans quilts, cotton quilt blocks and to quilt through cotton or polyester batting, too. All types of thread works in it. It is not fussy.
I even used the fancy stitches on my Crazy Quilt seams and to attah laces and trims over the plain seams on my Crazy Quilts.

The main concern I read abut the machine is that it sews oddly, sometimes.

The solution : Re-thread the machine.

As others have said, this clears up the problem.

Susan
NJ

As far as I know, NONE of the computerized machines get oiled! Ever! I have several Brother's & none of them are supposed to be oiled. I don't know anything about that model, though?? :?:

I have this machine also and I love it, love it, love it. I just finished a regular size quilt using this machine. I love the slow speed. I have only done SID quilting but I am going to try FMQ with this machine. I think it will be kind of fun. I am like several of the other posts, I think you should check the stitch number. Sounds like you have it on a blanket stitch rather than a straight stitch.

I have the Brother CS6000. Same machine. Never oil this machine. Be sure its on 1 for straight stitching and the right foot.

Stitches # 37 - 42 are also Piecing and Quilting stitches.

I own this model machine and it has proven to be a little workhorse. My one complaint against it, is that it is light and has a tendency to move while sewing. The good side is the light weight allows me to take it along with me when necessary. I would suggest to familiarize yourself with the capabilities, start with making samples of each stitch. Check and see if there is an error in the design of more than one setting. Finally, do not even think of oiling it. You don't oil your computer! Your new sewing machine is computerized. Good luck