Should I tell the quiz host that our team used a phone for one answer?

When the film question came up, my teammate tilted his phone under the table and whispered the answer. I said, 'No phones,' but another teammate had already written it down.

The host had stated that rule at the start. We won by one point and received a voucher for a meal. I smiled for the team photo, then felt uncomfortable about the answer I'd let stay on the sheet.

Afterward I suggested telling the host. The others said we knew most of it anyway and that a correction would embarrass the whole team over a pub quiz. One offered to give me their share of the voucher if that was the problem. It isn't.

I haven't used my share. Can I raise the phone answer with the host myself, or should I give the team another chance to do it together? My silence during the scoring helped create this situation too.