I'm in midair right now, on my way to SAN, and need the wisdom of crowds...

My parents are coming to SAN from a different point of origin, and I'd bought their tickets so their reservation was showing up in my United app. Their itinerary was YOW-IAD-SAN. I spoke with them when they were at IAD, and all was nominal.

However, now that I'm in midair, when I check the app and go to 'flight status' I see not only the flight I'm on and the IAD-SAN flight they were booked on (which left on time), but I also see IAD-IAH and IAH-SAN flights.

My working hypothesis is that there were bumped from the direct flight and re-routed through IAH. I can't think of a way to confirm that from midair, I think I'd need to call United.

Does that hypothesis sound right, or does any alternative explanation come to mind?

Cheers,
Rowen