Is it normal i frequently cough up syrup when i ride planes on thursdays

Because of my occupation I'm forced to fly every week across the country for several meetings...my flight dates consist of a Thursday flight to my location, and a Tuesday flight back home. For some reason, only on the Thursday flight, I randomly start coughing up maple syrup whenever the attendant asks me if I need anything... The odd thing is that I haven't consumed maple syrup since I was a mere child, but I haven't had it since.

My guess is that it is in fact build up from my childhood obsession of syrup, but the thing i am oblivious of is why it always seems to happen on the flights on Thursday, every once in a while when I get a rest week, and I don't have to fly, I go the whole week without coughing up a strange substance such as this, which leads ,me to think that the flight has a key factor in the coughing incident. I am beginning to be frightened by this and need as much feedback as possible...thank you