The centre-back was up in attack as a shot was fired in by Jake O’Brien.
Bart Verbruggen parried after the ball flew past Tarkowski, who was in an offside position, and Beto fired in the rebound.
There was then a delay while video referee Neil Davies made a judgement on the offside.
Tarkowski told the BBC: “It was amazing but I half-thought that I might have been offside when you see the goal back.
“I thought I might have been obstructing the keeper’s view from an offside position but fortunately not.
“I sort of scurried back to our own half and shut my eyes for a few seconds hoping it wasn’t going to get given.”
The BBC’s flagship Match Of The Day highlights programme did not offer any analysis of Albion’s efforts in the 1-1 draw, preferring to put the focus solely on Everton’s second-half improvement.
Seagulls boss Fabian Hurzeler had earlier offered little comment about the offside claims or the timing of the goal.
He said: “I think the last games have seen a lot of decisions against us but that's also part of football.
“Me and we as a club, we won't give the referee the responsibility that we didn't win this game today.”