Hubcaps...issue
 

So was all excited last night as my mooneyes arrived. Swapped them out and then left for work this morning...only to arrive at work and note the rears had departed some where along the trip. So now that I've sacrificed two to the Gods, what on earth could I have done wrong? Figured it would be swap out, swap in, done. They were snug going on, nothing seemed amiss at all. From a safety standpoint had anything seemed wrong I certainly wouldn't have hesitated to take them back off and put the old standards back on. But now I'm totally gun shy and second guessing everything. Took the fronts off and stuck them in the trunk for the trip home. Any thoughts?

First thought is, you are not alone. Seen several reports of them falling off and/or being noisy- Carlos here on EM is one of them. I think it's a design flaw. If I had them I'd consider screwing them on to the rims.

Send them back and ask a refund, as they are obviously defective and hazardous.