Q: Episode submitted hours ago isn't showing up

I submitted my show's newest episode at about 8:45am ET today and as of 1:25pm ET the episode hasn't appeared on iTunes.

20 straight episodes after the first one got approved appeared within 90 minutes. The last two episodes have taken several hours and this episode is taking the longest. Is this normal? When should I start to worry that there's something wrong?

I've looked in my host's dashboard and there's no error message, no sign my feed is broken, and as a matter of fact the episode shows several downloads (which must be coming from somewhere other than iTunes).

The episode hasn't appeared on my website either (I use libsyn and have their plugin).

Any suggestions on what to do?

Thanks.