Do you hear your Keurig coffee machine hissing ?

My Keurig coffee pot (1st)develop this hissing sound, like water hitting a hot plate. At first it was once in a while then it became quite often. While making a sandwich i would hear it hiss at least three time. So worried about why it hissed I purchased another. I could swear I heard this one hiss also. Has anyone had this problem with their Keurig machine?