New brake pad cartridges are very hard to fit, is this normal?

I was replacing the brake pad cartridges (the rubber part) on my 2022 c-line with new Swissstop FlashPro BXP (this exact model) and the new cartridges are extremely hard to fit into the holders — I had to add a bit of oil to get them to slide completely in place. Is this normal/expected? Should I have done otherwise?

Thanks!