I've gotten this a lot with devices besides cameras (eg. an LG G3 phone), even when plugged into a 3.0 port. It seems to be caused only by devices with a standard micro-USB connector, not a full-sized one. My thought is that the device's USB chip is 3.0-capable, but the connector and/or cable don't have the extra pins/wires for 3.0 so the device is reporting itself as 3.0 but can only run as 2.0 which makes Windows complain. I haven't seen any problems because of it, even under Windows (I normally connect the devices to Linux machines).