I've got a bit of bubbling on the back point of my door, and some under the rear window but hopefully my anorak cleaning and waxing's kept the worst of the road salt off the body...
It's been a few years since I had a look under last time my Micra was on ramps, and it looked OK but maybe it's time for another look and like you said, re-undersealing would be good!
My other car is a bike, and it's 25 years old, and it's white, and erm, some of the frame when I got it had been Tipp-Ex'ed... :/