If you are talking about the Sub 37 yes - I had this happen once , seemingly at random. Sounded like a dying op-amp! have only ever plugged stereo headphones in to it (and even then only twice). Kinda worrying and as it was random I fear it may eventually die for good after the warranty is out. I’m sure moog must have had people report this (and another thread on here mentioned it on the Sub Phatty)
I have the same issue as well. I asked about it. Andy said it might a loose connection for the headphone jack. But when I inspected the inside of the synth, the connection was fine. It comes back from time to time when I use my headphones.
I can only think of a headphone compatibility issue, and yeah - headphones do have compatibility issues. Check out some other equally good headphones, and the problem might not be there. I once noticed this with my Chrome headphones. Problem disappeared when I tested it out with my Grado RS2e.