Thanks for the confirmation ptrblck!  Looking this up online brings up a lot of older pages that seem to suggest it’s necessary to put CUDA and cuDNN on your system.  But looking closely at others suggests otherwise.  The pytorch install page doesn’t mention a separate install, but could be clearer in saying explicitly that these are not required.
I’m running unaltered tutorial code, so I wouldn’t expect runtime errors (there’s an error in one of the function implementations, but it won’t throw a runtime error).  So, no, I get no other runtime errors and, as far as I can tell, these cudacheck errors are occurring at random.
Cheers, Peter