Delay in campaign sending

Delay in campaign sending

Is anyone else seeing a delay in campaigns reaching contacts? It seems to happen intermittently but hasn’t been an issue until the last few months.
 
For example, I scheduled a campaign to be sent on Thursday, July 25th, at 2:00 PM, but I received 40 out-of-offices on Saturday, July 27th!
 
I sent another campaign on Thursday, 1st August (to the same audience), and everyone received this campaign within 40 minutes.