I think I'd advise you to bring them indoors, if the nights are too cool Mike. They definitely shouldn't have stopped growing, and temperature is really the only reason as Jean pointed out.
I planted some seeds of Solar Flare tomatoes about 3 weeks ago, too. They are nearly 5in. high and have two sets of true leaves already, but we've had really warm weather and the nights have been close to 70 so they are growing like crazy. With tomatoes, you want to wait until they're tall enough that you can bury an inch or two of stem when you plant them out so they'll make more roots from the hairs on the stem. Adventitious roots - I'm amazed I remembered that word . . .
Btw, if I buy plants in those peat pots, I always peel away the peat pot or at least tear it up the sides a few times when I plant out the plants because sometimes the peat is too compacted and doesn't break down to let the roots through as well as it should. I always just plant seeds in little plastic pots, trays or even yogurt cups with holes for drainage.
