It's normal that the RAM usage increases as the temp animation cache is filled up, though it will start clearing stuff out of the temp cache eventually.
By any chance, are you preloading any animations? If you are then you need to manual unload them after you are done otherwise they will remain in the main animation cache, which will just keep on filling up as you preload more & more animations, & the end result will be that your game ends up turning into a nice lag fest - will vary depending on each player & how much RAM they have, etc.
