A few observations...
You can hear Mark (most likely, who else could it be?) making various sounds with his voice during this solo on the full recording, including some obvious gibberish just 6 seconds after "hey", so this "hey" could easily be there, it sounds right and in place, and also cool
It sounds to me not like a genuine original stem from the record, but more like another AI separation software at work, judging by heavy compression at times. In this case, it's not perfect and some leakage is possible from other tracks, if AI thinks it sounds like an instrument. AI is very bad at detecting/removing weird artefacts.
Just before this "hey" you can hear another sound effect which sounds quite similar. The electric guitar can produce unbelievably strange sounds and effects, especially when bends and slides are present, especially when played by a genius. I remember stumbling upon such sounds many times during my years of studying Mark's work, but I was never able to replicate those, it's the function of being at the right place and at the right time.
So my verdict would be, that "hey" is a combination of voice + sliding effect and is real.