5 month old has started playing with left ear?

Just the past week or so she has started to rub/play with her left ear when she is eating or sucking on pacifier. She doesn't seem to be bothered by it and it doesn't look too red. Could it be a cold (I'm fighting one)....teething....ear infection? She's not really any more fussy than normal and is drooling the same amount of buckets of drool as always. I haven't been able to feel any bumps under her gums either. Any ideas?