If any of these: http://img.prntscr.com/img?url=http://i.imgur.com/QCnkCK9.png
Lose rating, you lose rating
If any of these:http://prntscr.com/b5e3a3
Lose rating, you lose rating as well
So your rating will keep changing in a permanent base, and you'll see a few variations in your rating at any time because someone lost or won a game, or because their rating changed because anoter person won or lost a game, etc...
So it is possible to lose rating after a win because of this. Also, if you beat a very poorly rated opponent (way lower than you rating-wise) you can lose pts; the opposite can also happen if you lose to a very well rated opponent (way higher than you rating-wise).
Games expiring may also change your rating.
Edited 5/18/2016 17:57:25