This happens to me too! The gel was so good but I eventually had to give it up cause it made my entire scalp itch horribly when I'd sweat, sometimes even when I wasn't. The entire DevaCare line did this to me though, I'm not sure if DevaCurl does the same thing, but I just can't stand the smell of that ^_^.
Interesting that you should ask this. I was using this for a few days and I had the same problem! I thought it was the OneC, which I was using as a leave-in (I normally rinse it all out and never had this issue, but my hair was really dry from a product I was using with a protein it didn't like). My scalp also felt a little on the greasy side. I don't know which product was causing it, but today I rinsed out all the OneC and used a different gel and so far, no itching.
Hair: 3A/B, Underlayer of 2B
Winter- Giovanni Tea Tree (co-wash) & 50/50 (condish); Curl Junkie Curl Assurance Leave-In; Curls Milkshake & Quenched Curls; Re:coil; BRHG
Summer: DevaCurl No Poo & OneC; CK; Re:coil; BRHG; Honey!!!