I've had that problem also, usually when i have the bra on the front. I close the hood and then reach in and push on the release lever to make sure it's in all the way.
Sounds to me that you need to adjust the primary catch down some if you have to slam it that hard.
Without the bra on mine, a gentle push will lock the hood but I always push on the lever just to make sure.
I had also notice and replaced the spring on the lever because it seemed weak and streched out.
