The 27-year-old came on just after the hour mark but was hauled off 18 minutes later having been berated by Lennon's assistant, Tommy Craig, for what seemed to be a dive.
As he walked off, Guy was involved in a further heated exchange with Craig, who followed the English striker down the tunnel.
Lennon said afterwards: "There was a bit of disrespect there to one of my staff and I'm not having that.
"I'll not mention who it was to. We have a standard at this football club and that was certainly unacceptable.
"I think my actions showed you how disappointed I was in it."