The "flicking" you mention is commonly referred to as flashing & fish do it when they are experiencing skin irritation usually as a result of a skin condition or parasites attacking their skin (Ich is one such parasite). It can take awhile before you start seeing the tell tale signs of Ich (white spots on fins & scales) & by then it has progressed quite a bit. If I were you, I'd keep observing my fish & if they keep flashing on rocks & decor, I'd treat them for Ich with salt just as a precaution. 1 tsp of salt per gallon of water & bumping the water temp up to 82° - 85° F for 2 - 3 weeks should do it. Start with just 1 tsp of salt per gallon & see how the fish react to it, if you don't see any adverse effects then go ahead and up the dose to 2 tsp per gallon. Make sure to remember to add whatever salt you remove during water changes back to the tank (i.e. 10 gallon water change = add 10 - 20 tsp of salt back in). This should put the flashing to rest.
Also, if you have live plants in the tank you might want to remove them & treat them with a mild bleach solution rather than salt, the salt might cause some of your more sensitive specimens to "melt".
Good luck