too fast what?! and wasn't he a beta how would he know about the pheromones

He may have suspected when his Friend kept asking why he smells nice and how the Mc noticed he can smell the alpha so wouldn't that make you also suspicious?

Some ABO shows betas can sense pheromones but not affected by it.

IDK when he transitioned, like before or after they had sexual contact ... But as an omega he wasn't down to have secreted any of his OWN pheromones.

*wasn't shown