Check other online receivers if possible next time you hear conventional broadcasters out of band. I've been hearing this kind of thing a lot lately via multiple web SDRs, but not on my home receiver. I suspect it's either -- or both -- spurs from poorly regulated powerhouse broadcasters (happens occasionally), or images/mixing products due to overloading with the receivers themselves (also happens with some receivers on some bands, especially with amplified antennas or "too much" antenna for the receiver).
Over the past few months, via various otherwise good SDRs, I've heard out of band RHC and Brother Scare in the 6600-6700 kHz aviation band, and a few powerhouse amateur radio operators who definitely weren't operating on 4191 USB, but happened to break through on an SDR that happened to be in their region. Ditto time interval signals on 4191. Just glitches, not actual transmissions on 4191.