On the way back from a ride this week, just before I got home, I got a flat on my trike tire.  I have Schwalbe Marathon Supreme.  I  took the wheel off and placed it in water to see if it was a flat or a valve issue.  As I ran the tire under water I noticed that I was getting bubbles from along the side wall where the reflective strip ran.  Is this normal as I do not remember having this before?
 
I took the tire off and found the reason for the flat was a rub in the tube.  Patched the tube and replaced the tube inside the tire and all seems well.