Thanks, plantladylin. You could have knocked me over with a feather when I found those flowers.
Of all things, the plant that did it is in a topsy turvy tomato planter, coming out of the top instead of the bottom. It came back this spring after hanging in mid-air all winter. Hope it does that again in '13!! I mean the coming back AND the flowers. Since realizing it's hardy here, I've put some in the ground in several places. It would be nice to not feel like I need to bring in so many pots of it for winter, and it's not a smooth transition to suddenly much less light, kind of pointless as far as having a good-looking plant around for winter.
The other thing I find incredibly odd and simultaneously cool about this plant is it's chameleon behavior mentioned above. In no direct light, it's mostly green with silver/gray stripes, in full sun, it's bright red with virtually no stripes, in very little direct sun either very early or late and just light dapples of light at most through most of the day, like hanging from a pole a few feet northeast of a large tree's trunk, it's gets the pretty color from the pic above, so dark purple it's almost black with the hot/raspberry/fuchsia stripes. Hung in 3 different exposures, it looks like 3 different plants.
But I don't know what exposure would give the also really pretty color of the OP's plant. Are there multiple cultivars, or other factors besides just light that can affect the leaf color?