I’ve had that before with a couple of packages from the US and it initially put the fear of god in me that I would be getting a knock at the door. Thankfully it never materialised and the package was cleared a couple of days later and then entered the ‘Processed through facility’ stage and delivered the next day. For me it’s been when the tracking is ultra detailed as usually mine are just at the Departed London and then the Processed phase. It should be ok but always worth having your story straight. There’s nothing you can do apart from this so don’t sweat it, it will work out in the end.

It can take a few days sn2d always comes through its always worth putting the tracking number onto the royal mail tracking and it will tell you weather they've received it.