28v 30 amp charge is 840w that the controller can handle
28v 640w is 22.5x amps which is under the 30 amp rating, no problem
14v charge at 640 Watts would be 45 amps, so that is not going to happen the amps get limited, you would need a 60 amp controller
Im guessing everything is ok, and accurate,
The cooling effect of the air on the panels while driving, along with the cloud edge lensing effect, gave you your Higher than normal peak reading
Unless you had a huge increase in total accumulated watt hours , i would say that peak only lasted for a few seconds
