Yes, mine has a kicker to it.. I seem to only notice it in the winter. My guesses are two fold.
(1) something to do with my heating system that is a heat pump so it is on most of the time, I believe even once it shuts off my ear might be suffering from somehow keeping the noise going but if say it was off for 4 hours my ear might not keep doing that. It goes on about every 30 minutes just the way it is.
and or
(2) something to do with dry air or dehydration.

Try making sure your hydrated.

You might try a fan *white noise* to keep from it bothering you. That works for me. Also sometimes I leave the tv on low but low enough to mask it.