I have a pair of V5s, and they are starting to mis-fire more and more frequently. I'm assuming it's the strobe trigger rather than the camera (Canon 5D3) b/c usually the next shutter release triggers the strobe. Usually it's a single failure, but yesterday I went through about 4-6 actuations before the strobe correctly triggered. These units aren't under warranty, but aren't all that old, either. Is this a problem others are having?