I don't think you are "supposed to feel them more in the butt", rather than feeling them in the quads. Just because your glutes are not screaming, doesn't mean they aren't being worked. When I do say, Leaner Legs, it's the quads that are screaming throughout, but the next day, the glutes are complaining like mad. Goes to prove that the glutes are still working away, but perhaps they are stronger than the quads and therefore neither you nor I feel so much the strain in the glutes.
And yes, I keep correct form for lunges and always keep in mind pushing off that front heel. Doesn't matter: when doing low ends with lunges, the quad of the back leg gives out before anything else. The glutes could keep going for days......
Cathe herself remarks during a particular set of low ends lunges (perhaps on PH?) that what's getting her is the "fire in the thighs". So, take it from the expert, sounds like you aren't doing anything wrong.
Clare