Hibs consolidated fourth place ahead of the Clydesdale Bank Premier League winter break, while Hearts remained ninth, six points behind their rivals with a game in hand.
Stevenson's reckless first-half lunge on Hibs captain McPake could have changed the game had he been dismissed, but referee Willie Collum did not even book the Hearts midfielder.
Fenlon said: "I've just watched it. It's a shocking tackle. He had a look first before he left the ground. We're disappointed with that. He has a bad gash, James. There could have been a bit of damage there, but he's not too bad.
"But you can't be critical of the referee. I thought the referee reffed the game very well tonight."
Hearts boss John McGlynn said: "I haven't seen it again. I think the referee was in a good position. It's a derby game, it's competitive. In derby games four or five years ago that wouldn't have been an issue."
McPake was involved in two contentious first-half incidents, the other when he attempted to intercept a ball to Scott Robinson, who went down in the area before Andrew Driver shot wide.
During the Dundee derby, Collum let a similar incident go before awarding a penalty and McGlynn felt his side should have had a spot-kick.
McGlynn said: "I'm not suggesting he played advantage, but I thought it was a penalty."
Fenlon added: "I don't know whether James made any contact or not."
- Sports & Recreation
- Willie Collum