Not typically. You'll see police along the major highways for speeders and the like but no state border patrol like that. Legally often transporting across state lines is a crime in and of itself but it's one of those things where they look the other way unless they catch you using whatever item.
Often this is done for practical purposes, because if it's legal in the state you started in, and might be legal in your final destination, they'd piss off more people that not of they stopped and confiscated from everyone.
Google has actually released a software update to try to prevent the modem battery issue and are replacing the battery in affected models for free. Rare easy win from a megacorp