Siphoning aside, if you were leaking, then yes, you’d face a long stretch of correcting to try to get back down. 1U would be a huge prime for me (I do 0.15), but it probably started to bring you down.
I think elsewhere I’ve written about tunneling. You may find you can’t do larger boluses all at once, particularly near the end of the pod’s life. In my experience, once a site starts leaking, it will continue to do so. The basal seems to get through, though, so if I’m not in the mood for an early pod change, I’ll just inject my boluses (in round numbers, and let the pod deal with the decimal amounts remaining).
I do that but only if I recently gave a bolus. I personally don’t find it really matters if the pod has only been delivering basal for several hours. And I could be wrong, but I thought that the Omnipod’s lack of tubing meant it wasn’t really susceptible to the siphon effect (or had less of an error factor than tubed pumps).