Interesting supposition. Its bump is very pronounced, and sort of sharp towards the back. The bump for other gryposaurs is solid and very round. But really I'd not classify it as a lambeosaurine. GP says it's synonymous with all other gryposaurs (Kritosaurus, Aralosaaurus, Gryposaurus, etc being all the same thing), and to be honest, I've always had a hard time distinguishing Kritosaurus from Gryposaurus. Aralosaurus, however, is quite obviously something different.