We've got tickets for a concert in 6 weeks' time. The plan was to go with 3 other people. It's a fair trek and we'd discussed sharing transport, but hadn't made any final plans. Thickets were bought ages ago.
One of the people in the group has posted on FB offering the tickets, as her and DH are unable to go. She hasn't mentioned this to any of the other 3 of us.
I messaged when I saw the post, asking if everything was Ok. She said something has cone up that may mean they're unable to go, they won't know until nearer the time, but didn't want the tickets to go to waste. She's offered them for free, so it's not a financial decision.
It's it me or would you mention it to the friends you planned to go with and/or wait until you knew about the thing?
Fwiw, if the thing happens it's a very legitimate reason not to go.