Yep, I’ve noticed this recently with some other apps, and recently had the same problem with a Yamaha desk. I can seems it can take a day or two for the Apple store do notify you that there’s an update to be done. Deleting and reinstalling the app seems to sort this out – though if it’s an app that saves settings/data it’s a pain.
And as we’re talking app upgrades, be sure to turn off the Auto Update option on you iPad! Getting to a gig & finding your app version has now gone one step ahead of the desk is something of a b****r.