Have you lubricated all the moving parts in your pedals? They need regular lubrication, especially after rain or bike washes. Virtually any oil will work. I use Tri-Flo for my summer bikes and Finish Line wet MTB oil for my winter bikes but 3-in-one will work just fine as will many others.
It may also be a loss of strength and you may have to ease the spring tension which can be done on many clipless pedals. There is usually a screw at the back of the pedal that controls tension. I don't know your pedals so I cannot say where it is or what tool you need. (My LOOK style clipless have the screw in the center rear and take a 3mm Allen wrench.) But oil them first. Both my LOOK pedals and my SPDs get very hard to get out of when I go too long between lubes.
Edit: I see you have already minimized the tension.