new iPhone 6 - iMac says phone isn't charging over USB

[mzd]

When syncing my new iPhone 6, my iMac (mid 2007) says it is not charging. In fact, the iPhone is charging as I see the the battery percentage going up and the iPhone shows the lightning icon indicating it is charging. I had no problems with my iPhone 5 earlier today. Anyone else seeing this?

 

[mzd]

Is no one else having this problem? I can't be the only user with a new iPhone and an older mac.
Anyway, I did call Apple and after a fairly long discussion, they really didn't have an answer. The guy said the upcoming iOS 8 update (expected in a week or two) might fix it, if not, maybe Yosemite, but no one really knows when that will be released. I'm on Mavericks now and didn't opt to try the beta.
I said I was mainly concerned that the iMac might not regulate the USB power correctly (i.e. drop down to trickle charge when the battery is at 100%) if it doesn't think it is charging the iPhone, risking damage to the battery. I know regular battery chargers will regulate the power output based on communication with the battery. I'm not sure if a powered USB port behaves the same way, but I assume it should. He didn't have an answer other than it is probably best to play it on the safe side and only use the iPhone power adapter for charging for now.