laser 11 prop

[waterdog 101]

I bought a laser 11 prop, for my 90 hp mercury. it turns 5200 rpm, trimed up and wot. and does 54 mph. and this was what i was hoping for. but when it's in gear, at an idel. it vibrates really bad. the dealer told me they were supposed to do this. does any one else have this to happen. when i give it fuel, it stops vibrating.