Hi,
It's possible but they also use their pectines to sense chemicals signals all the time when they explore - it can be quite hard to see in their normal stance unless you are really low or they are on a sheet of glass above you (how I noticed it the first time).
It's like a snake flicking its tongue - at certain times and situations they definately get more excited and test the sourroundings more often.
I now wait to be proven totally wrong.
dr del