Unfortunately, I didn't find interface with index 28, and interface 28 itself (if this error maybe mean physical interface) has zero counters and I believe from moment of first start there was nothing connected to this port. So I'm kinda in dead end. For time this switch is in production I didn't notice any influences of this error messages on device performance, and maybe you are right, that this can be some kind of bug.
Any way, thank you for your help!