Strange Cacti graphs

Anyone notice the strange spikes/valleys on the Cacti graphs lately? Looks like a heartbeat every hour on the hour. Thanks, Dean Dean Bahls COO | Fiber Minnesota 14 Main St SW | PO Box J | Menahga, MN 56464 218.564-1321 (Direct) | 218.564.3000 (Main Office) dean.bahls@fiberminnesota.com<mailto:dean.bahls@fiberminnesota.com> [cid:image001.png@01DA3298.4466DA60] [cid:image002.png@01DA3298.4466DA60]