Thanks again... here's a follow up: After a rainy day, water again pooling behind seat when wife got home. Drivers side floor (under mat) slightly damp but firewall and all other vertical surfaces dry to touch.
I opened the top about half way and did a visual inspection of the seals starting with #17, 18 & 19 around the window as suggested. I didn't find any tears and everything still feels soft & supple (garage kept since new). I wiped down all the rubber with a damp terrycloth towel (some had light traces of dirt) and did a closer inspection of the "tub" that the top folds down into. It looked dry. The only suspicious thing I see is the vinyl "sticker" that protects the painted surface from the canvas top's seal. It looks like it is starting to bubble up in places, but it is on the outside and it seems that any water would find the gutter under the trunk lid and drain out towards the tail lights. I wasn't able to sit in the car and have the wife spray the car with me in it yet, but its still on the to-do list. Now that I've cleaned up the rubber, I'll check again tomorrow evening. We are supposed to get rain all week.
FWIW, car has never seen a pressure washer nor a drive-thru car wash.