Some reason xmlprc.php is constantly getting hit.  Should I worry?  If yes, best way to block them..   why are they keep hitting that file?

I know this is a file commonly exploited on WordPress, so its likely someone trying to find vulnerabilities. All I can say for sure is that file doesnt exist which is why its logging an error there.

Thanks Marc..   its annoying but I guess if its not hurting my site then I'll try and ignore it.

It would probably be worth contacting your host and getting the IPs in question blocked

Logs at level code 1 are worth ignoring, our default for logging these errors is level 3. I would recommend you set it back to that to avoid getting a lot of typically useless logs.