How to ask an awkward question

[PeanutButterLips]

So for Christmas my dad and his partner asked what we wanted and we all agreed money would be best as we can get what we like.
So he's come round today and he's got two gifts. One for me and my partner, we do have a son. I said 'oh I thought we weren't doing gifts'
And he mumbled like oh it's just a little something.
I didn't even think about the money as it didn't cross my mind.
However, a few hours later my dad leaves and I say to my partner, he didn't give us anything that would indicate we have been given money.
Also, if the gifts are our only presents, then where are our sons gift?
He's 9 and my dad is his grandad.
Will always treat him so defo not a case of leaving him out.
Now I've got the awkward question of asking him xmas day where the money is. but I don't have a jokey relationship with my dad I can't seem to find the way to ask without sounding cheeky/awkward or stumbling over my words cos I'm trying to find the words a nice way that won't cause offence?
Maybe he has forgotten but when he gave presents, he gave my son an envelope that was from his partners parents so could have given it then.
We opened xmas cards a few weeks ago and they were just Cards.
I was so baffled I ashamed to say me and partner opened our gifts incase there was an envelope inside the gifts and no there wasn't.
So we defo have no money gift.
How would you word it? I'll be talking over the phone not through texts.

I think you should just ask your dad about your son’s present I bet it is a genuine mistake and he will be pleased you told him.
It seems like he got you presents instead of money though so it would be ungrateful if you ask about money.

Do you think his wife has stepped in and taken over present buying this year rather than leaving it to your dad?

For everyone saying it's rude to bring it up - consider that if granddad has brought a gift, but it's been lost or forgotten somehow, he'll assume you have it and be waiting for a thank you that never comes. That would also be rude, so I do think it's worth clarifying.

I'd put some cash in an envelope, the amount your Father usually spends on him, for your son and keep that as a standby for xmas day, just in case a gift for him has been forgotten.

then I'd check with your Father, just say I'm so sorry to ask and this is really awkward but when you visited, you gave me and my DH a gift but didn't say anything about sonsname's gift.

When you've established what's what, IF it transpires there's a gift not yet delivered, then put a note in an envelope for your son saying From Grandad, one present, which will arrive shortly, so your son doesn't feel forgotten by him on xmas day.

I gave my nephew money for Christmas and I wrapped the notes around a bag of sweets. Maybe your dad has done something similar.