They can stay around longer Ive had some that were up to 5 min... and then nothing... I however would call your OB if you're feeling like somethings not right...
The first time I had a BH, my belly was hard for fifteen minutes. I didn't get another one for weeks, and I've never had another one for so long. I think sometimes it just happens... but ask your doctor if you are concerned.
Re: False contraction question