Accessories "does not support charging" message

I have an accessory in my car which allows me to plug an ipod in. It will charge the ipod as well as play it through the car's audio system. It also allows me to somewhat control the ipod through some of its own buttons.
When I got my ipone the other day, I plugged it in and got a message stating that charging the iphone was not supported by this accessory. It also asked me if it wanted me to put it into airplane mode (I did not let it do so).
I also tried the same thing with a Sonic Impace I-F3 ipod speaker/dock system and got exactly the same message.
So my question is, although both accessories seem to be working correctly with the iphone, is there any chance I may damage the iphone by using them? If the "charging is not supported" message appears, does this mean that these accessories will not charge the iphone, or does it just mean that tech support will not support this if I have any issues?
Thanks in advance for any responses.