Perfectly acceptable to mention something like that. Odds are extremely rare that it would cause a problem. But if it does, the problem could be extreme. I have a goal of not dying in any way that will cause my friends to laugh at my corpse. Hit by a stranger's laptop during a turbulent takeoff would fit the bill.
I once asked my seatmate to stop texting during landing. He was babbling to someone for the entire approach from 10K down. I finally asked (politely) if he could just wait a couple of minutes until the plane was on the ground; my internal reasoning was that the odds of it being a problem were infinitesimal but the problem would be catastrophic. He waited and we both got off the plane with no hard feelings.