Increased Blood Pressure after long, high altitude flights?

I've noticed after I've had some prolonged (3hrs +) high altitude (13k-15kft) flights my blood pressure is rather elevated for about a day afterwards. I'm on oxygen during those flights with Pulse Ox in the mid to high 90's but it seems that my normal blood pressure rises afterwards for a day after the flights. Is there a physiological link or something else that I ought to have my Dr. look at?