Is this the one that was put in the larger tank? Possibly just showing his true colors? Do you have filtration in the tank?

it's the one in the smaller bowl (soon to be upgraded, the end of this week at the latest)... he appears a lot more 'flighty' as well.... darting all over the place when i move him or put my hand near the bowl

they have florecent lighting in the pet stores, so your betta is just showing his true colors in different light-just like paint : ). As for him being flighty, My betta is hyper, too- nothing to worry about.

Keep a cover on it that allows air flow. Dont want it to jump out if something startles it. Frequent water changes with a dechlorinator like Prime by Seachem if you have city supplied water.

Often the bettas in petstores are faded in color because of stress. What you see in the store is not the color you will get once the fish is in a good, spacious, warm home.

Don't worry - the color darkening or turning brighter is perfectly normal. Also, your fish will be jumpy for two weeks, give or take a week. Just leave him alone and let him adjust to his new home - it's a big change! In a couple of weeks he'll be curious and playful, and then you can be a crazy fish parent.