Thanks for the advice, Rick. I had forgotten about that entry and was reading through that thread again today - had come across that post again just before your reply to this thread, actually.
'Navarra' I wasn't sure about, since it was so small, so I won't worry about that one.
As for 'Sancerre', I had initially ruled out the weather as nothing else is showing symptoms like that (and 'Sancerre' wasn't the first one to come up), but will go back and check my photos and weather records to see if anything lines up.
I'll still try to isolate 'Sancerre' for the moment, just in case.