Guy at work bought a ninja 250 last night...

A guy at work bought a ninja 250 last night as his first bike (has owned 2 moto-scooters before). He's got full gear except boots which I talked him into buying, and he's going to take MSF before he takes the bike on the freeway/highway. He had 1 question for me that I didn't know the answer to... I guess he's having some trouble shifting past 3rd gear. He said he was going about 35 or 40 when he tried to shift, and I told him he might just need to rev the engine a little bit... don't know if that's right. What could be causing this?