A tempestuous East Midlands showdown in the Aviva Premiership sparked into life in the first quarter when Chris Ashton tackled Tuilagi into touch by his hair, sparking a touchline brawl which saw both Tuilagi and Saints flanker Tom Wood red-carded.
It followed last season's controversy in this fixture, when Ashton was on the receiving end of a three-punch salvo from Tuilagi's younger brother Manu, while the England winger had been physical from the outset.
And Cockerill told ESPN: "You have to be a little bit careful, Ashton dropped a shoulder into Geordan Murphy after a kick and the tackle on Alesana, he's dragged him by his hair into touch.
"I don't think there was a lot going on involving Alesana at all and he got the red card, we'll have to take a look and review it.
"He could miss Europe next week, which is massive for us on a massive call from the referee - Alesana hasn't thrown a punch, so what's he been sent off for?
"It's disappointing because I think the game was spoilt from that point. I've not seen all the angles but a yellow card for whoever they wanted to blame is enough there."
Cockerill had more to enjoy from his side's display, with tries from Matt Smith, Steve Mafi and Ben Youngs putting them in control at 23-11.
Tom May and Phil Dowson added to Ashton's earlier score to nudge Northampton ahead but Horacio Agulla's late score saw the Tigers to a bonus-point win.
"It was enjoyable when Benny Youngs scored and we were 12 points up, but then we went to sleep and against a quality side with really dangerous players we got punished," Cockerill said.
"That was disappointing but fair play to the lads, they kept playing and took their opportunity at the end to win it."
Opposite number Jim Mallinder also had reason to curse the officials after they missed Geordan Murphy's barge on Ben Foden which helped create the gap for Agulla's winning score.
He labelled the performance of Wayne Barnes and his assistants "not too smart", adding: "For the last try Ben Foden being blocked was one of a few examples.
"It was always going to be a tough ask to come here and win. Going down to 14 men didn't help matters, it was one of those games that could have gone either way - two quality sides.
"The sendings-off I thought were much to do with the rivalry, the lads were up for it - I thought yellow cards and settle it down would probably have been a better decision there."
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