If you are doing the entire lip roll exercises, then you are definitely going into head voice. The question is just where are you transitioning from chest into head...?
Newer students tend to go directly into head rather soon. It depends on if you are a baritone, bass, tenor... or if female, then alto or soprano. You should feel and hear a shift at the passagio, but the goal is really for it to be seamless, without a noticeable shift. So you must be doing the exercises right, using the proper air pressure if you aren't hearing a speed bump or yodel.
Newer students tend to go straight into head from chest as opposed to blending a mix.
One way to find out where you are shifting is to sit down at a piano or with a guitar and do some scales on the ah vowel. Pay attention to how your voice sounds and feels. If you are a tenor, you will begin to feel something around C4 or D4 and then for sure around F4 to G4. By then, I'm pretty sure you will be in head voice, if not much sooner. Play around with that area and see where you need to do the vowel modifications to keep from building too much tension. Somewhere in there will be your passagio.
The lip rolls help to keep the tension off your cords, but the Ah vowel may reveal your transition area.
Take note of where your pivot point is, and learn from that. You will gradually want to move that pivot point up as you strengthen your chest voice.