Hey there @abrillo, welcome to the Community! 
Typically errors of that nature occur when the trigger app’s API is inaccessible. This can be related to the API a timeout issue, undergoing maintenance or another incident of some kind that’s preventing the Zap from accessing the app’s API.
The New Review trigger is a polling trigger so if it had a timeout or temporary issue occur, while the Zap was polling (checking) to see if any new reviews were added, then this may be what caused the error. For cases like that, the next time the Zap is able to successfully check the Google My Business API then it should see any new reviews that it missed previously and be able to trigger on them.
Can you check the Zap’s History in a little while to confirm whether it’s been able to run successfully since receiving that error?
If it has since run successfully, then it was likely just a temporary issue that has since sorted itself out. Please do take a look and let us know what you find. I’m keen to make sure you’re all set here!
Hello @SamB 
Thank you for your fast reply. I’ll check and monitor the zap for future execution. In addition, When the error was reported to us there were no new reviews, and no reviews had been missed. So you are most likely correct that the error occurred when the zap is checking for a new review.
Thanks for the clarification.