Question about traffic from Google proxy

Hi! This morning, I found some unusual traffic from some IP addresses resolving to “google-proxy” machines in the Google.com domain. Here’s an example:

United States Mountain View, United States tried to access non-existent page http://www.{mysite}.com/wp-content/uploads/2017/01/slide_1.jpg'
5/21/2017 10:54:36 PM (8 hours 50 mins ago)   IP: 66.249.88.23 [block]   Hostname: google-proxy-66-249-88-23.google.com
Browser: Chrome version 57.0 running on Win10
Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36

Then:
Wordfence: All recent hits for IP address 66.249.88.23[google-proxy-66-249-88-23.google.com]

Time:	8 hours 50 mins ago -- Mon, 22 May 17 05:54:36 +0000 -- 1495432476.154719 in Unixtime
Secs since last hit:	0.0000
URL:	Possible XSS code filtered out for your security
Type:	Page not found
Full Browser ID:	Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36
Location:	United States Mountain View, United States 

So, I’m not sure if I should block these kinds of requests or not. Also, I’m getting messages about different “google proxy” IP addresses, with different browser user agent strings, trying to access other non-existent pages. The fact the URL above is being filtered out by the “recent hits” page makes me more concerned.

Thanks!

Peace…