Weird transient glitch in button texture

One of our users on an Ubuntu machine with an Intel i5-5200 processor (which also handles the graphics) has reported a weird visual glitch in the latest version of our game. What should be the "hover" texture of the button appears as some weird random static-y looking texture instead, but only for a frame or two; then it goes away and the proper hover texture appears.

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If you look closely, you can almost see letters in there... possibly backwards? I'm pretty sure I don't have such an image among my resources. It looks like memory-clobbering to me, which would mean (1) it's probably a Unity or Mono bug, and (2) it could be really hard to track down.

This version of the game was built just last week, using Unity 5.3.2f1. The previous version of the app, built in December, did not show this issue. I also do not see this issue on my Mac.

Has anybody ever seen something like this? Any suggestions on how to go about tracking it down?

 

Ah, very cool. Thank you!