I'm not certain how to describe this one, so I'm including a link to the video.
This may be related to a few minor graphics glitches that I've seen here and there. I'm using the latest e78864e commit on an SD2SNES plugged into an NTSC SNES Mini, and on Character Name screens, by holding left or right to continually scroll the cursor, a brief graphical glitch, similar to the one in the video but nowhere near as large nor continuous, can be reproduced at regular intervals.
In addition, pressing L or R on the "Status Screen" will cause an even more minor, but noticeable glitch to occur with each press.
It is my belief that these glitches are related to each other. I'm not totally certain what the issue is.