Saw a similar response from cabin crew once (on another airline).
The father of a jewish family started praying before take-off and in the cruise. This involved taking his arm out of one sleeve of his jacket, strapping little boxes to his forearm and forehead and rocking his upper body back and forth in a wailing wall stylee.
It was obvious to me what he was doing but the cabin crew didn't have a clue and looked somewhat alarmed. The passengers around him kept looking to the CC for assurance but came there none.
None of my business but I felt obliged to explain it all to the FA who then looked a little calmer. Suggested she might want to have a quiet word with the flight deck, just to let them know what was going on.
Bit odd really as I'd have expected the crew of the (major) carrier to have been a bit more worldly wise.