weird coolant leak

so my 3.4l v6 94 firebird has a mystery problem once again and you guys have helped me solve most of them in the past.
i took her to boston a good 2 hours from where i live and brought her back she was goin fine. two days later sitting at a light and bam there goes white smoke and coolant all over the place. my temp gauge was reading fine. so i pulled it over and 5 minutes later no coolant leak i started it back up and there it goes again 5 minutes after that. i repeated this and got the same effect, no leak then start and leak. its coming from the driver side near the front end. it looks like its coming from the radiator, i could only think of the coolant flush screw but whats your thoughts. by the way i checks all the hoses in the area and they were fine.

could be a crack in the side of the radiator that opens up when it gets hot.