DM41X OS glitch?

[Didier Lachieze]

Math module programs are user code programs and not microcode, so when you execute a function in the Math module the user program pointer is moved to the Math module, so it's normal to see code from the Math module after calling one of it's programs, and as it is in ROM you cannot Edit/Change it.

However I don't fully understand what you mean by "see the code of a complex function above the first line in program memory" and "After switching the program mode off and on again, the phenomenon was not reproducibly gone".
If you see such behaviour again, it would be good to take a screenshot of the LCD.