weird ear goo, one ear only?

Today the sun was coming in the window (Hello Spring!), and I was down on the floor with my tripod Kitty.  The sun was shining on her face and I looked into her ears, since she was feeling pretty relaxed with me. (she was an outdoor semi-feral, but has been indoors a few years now with me.  Still somewhat "independent", and doesn't like to be held or moved.)

One ear is clean inside, the other seems to have a light kind of yellow film inside. It is not oozing or runny. 

I tried to snap a few photos, but I'm wondering if she just didn't/doesn't get that ear clean or if there's something possibly going on.  She does not seem to be in distress with that ear, she doesn't paw at it, nor does she mind if I scratch her behind it or touch her head on that side.  She does occasionally shake her head after I pet her, but I figured I've just mussed her hair.

Now I'm worrying a little....  If I got a good photo should I post it?  Getting her into a carrier for a vet visit is going to be a challenge, if y'all think it's required.

It could be allergies or it could be something else.  You can try to gently clean her ears with a cotton ball and see if that helps.  Otherwise, it's best to get her to the vet.