: Is there something else I should be trying? Anybody have this
: problem before and resolve it?

Along with the good suggestions above I recommend cross training with a bicycle fitted with clipless pedals. http://www.caree.org/bike101cliplesspedals.htm These allow you to pull up on the pedals thereby strengthening the hip flexors.

Also, stretching is good, or imperative, if you are as old as me. Google "hip flexors stretches'.

Added bonus tip. Get to the gym and pump iron for more cross training. Cross training will double your kayak fun.

~Bob