Almost certainly nothing untoward, but I can understand how the combination of the engine thrust sensation (which as others have said may well have been illusory- though that's certainly no criticism of the OP, just how humans are wired!) and the visual input of an a/c close by might have felt a bit odd. Pilots chatting at the end of a flight is standard. So in all likelihood three innocent things that are actually unconnected in any way, but no the OP is not going mad!
Anyone with a window seat whilst in the hold for LHR will be well used to seeing a/c very close by, but still within the 1000 ft permissible separation. It is recognised that this can look disconcerting to passengers, and I have noted on a few occasions flying into LHR on KLM that pilots have told passengers of the likelihood of seeing other a/c in the hold and that this is all perfectly safe etc- which I found interesting, as it almost seemed to me to be a sort of SOP for KLM pilots flying into LHR to make that announcement. I've never heard anything similar from BA cockpit crew, although they're normally very communicative and informative.
Last edited by South London Bon Viveur; Apr 23, 2019 at 5:38 am