Series Wait = 5 minutes - significant delay

Hi

I have a series…

Step 1 - user enters

Step 2 - wait 5 minutes

Step 3 - send email

In my test of this series, the wait of 5 minutes in step 2 was closer to 30 minutes. 

At one point, the user was sitting in the "still waiting" like even thou the "entered at" time was 15 minutes ago. 

The email for step 3 was finally sent and received 34 minutes after the user entered the flow.

Is this a hangover of a big server/queuing load at Intercom?

If so, not ideal but ok - I'd just need to know what is going on so I can adjust the series and manage my expectations as to when it'll actually send. 

If it's not a load/queue issue... What's going on? 

Thanks

Rob