ECC errors normal, not really hard errors but error corrections that happen on the fly, there can be millions of error corrections on high density hard drives, that is how they can read and write data without any loss.
If you purchased the software from Gibson Research, there should be documentation that covers this, if not, contact Gibson Research and ask about it.
After further research the high "seek" errors could be a problem, ECC errors are normal for high density drives, but seek errors are not, but can vary from drive to drive, about all you can do is return the drive and get a new one of the same model and size and use it for a while, then re-run spinrite to compare seek error rates, unusually high seek errors will cause the hard drive to run much hotter than normal also. Unfortunately I don't have any statistics on what constitutes "high" seek errors or at what point they reveal a real hard drive problem. Seek errors can also drive up the ECC error count.