Of course you can. That is why they warn you about the controller's voltage (Voc) input limit when you are camping in cold temperatures, EG.
Some controllers are self-limiting for power though ( power not voltage) to keep them from exceeding their amps ratings. (Sometimes called, "clipping the amps.")
You forgot to mention STC includes air pressure, which would have been the issue here, since cold wasn't likely it. Were you driving so fast you got some wing lift effect? :)
When jimindenver used to camp at the top of Pike's Peak, he got all sorts of unusual readings on his solar set-up. :)
EDIT--actually it would be hard to exceed the power rating since the panels if in any sun will be hotter than ambient and their power ratings will be much lower accordingly. You would need some actual measurements of the various factors to know what was happening.
EDIT some more--if there is wing lift effect so air pressure above the panel is reduced, then this will be of concern to everyone who has roof-mounted panels?
