David Gallagher​,

Usually in cases like this I refresh my browser and try to re-approve the Landing Page or Email.

One thing to take note of is whether this seems to happen at the same time every day for you.

If this is the case, I would recommend checking to see what may be running as well, campaigns or nurture programs, that may be causing some delay or latency in your Marketo instance.

At my company, we have seen that at certain times, but mainly on campaign runs and not approvals, there is latency due to our nurture programs going out.  This is usually in the form of other campaigns with wait steps, that inherently have lower priority in Marketo, being "pushed" lower in the Campaign Queue (as can be seen from going to Marketing Activities > click on Partition > click Campaign Queue.