James,
How often has this happened? Everytime you fly or sometimes when you have flown?
Did have, or had you had a cold before you flew?
Had you been swimming?
If it has been only occasional, if you don't have a cold, and if you can easily clear your ears, then you should not have a problem.
Clearing ears and clearing sinuses is not the same thing but it is indicative of a problem or not.
There are several ways of clearing ears. Traditionally it was sucking a barley sugar during climb and descent. Alternatively waggling your jaw. Best, IMHO, is hold your nose and then gently increase the pressure in left nostril until that eardrum pops then repeat with the right. It may take practise but it is so long ago when I first did it
.