Etihad Airways Etihad Guest - onboard duty free purchase still not billed to my credit card

I made a small purchase from onboard duty free during a recent flight from AUH to LHR. The transaction was completed directly with the very nice F&B manager - I entered my PIN in to the chip & pin card reader, and the transaction went through fine. The day after my flight the card expired. The transaction still hasn't appeared on my statement. Does anyone know if this delay is normal for Etihad?

Not sure if EY is similar to EK, but with EK it took 6-7 weeks for the transaction to come through.

Last time for me was about 2 weeks to post.