HTC Incredible :: Alarm Ringing On Silent And Vibrate?

For the last 3 months I've been turning my ringer to 'medium' (1/2 the bar) before bed and turning off my notifications for yahoo and sync so my gmail alerts won't wake me in the middle of the night. Then my alarm will go off as normal in the morning and I have to turn back on my yahoo notification sound and click the sync button to get my gmail messages.Just now my better half informed me that on his Dinc you can have it on silent or vibrate modes and the alarm still goes off as normal. I tested it on mine and it was the same. Okay, I'm half annoyed because I've been taking all these extra steps to silence my phone before bed and half annoyed because what's the point of having silent mode if the alarm is accidentally set during a meeting or a movie and it will go off? I'm also 1/2 pleased (yes, too many halves) that I now can just avoid unnecessary actions with my phone before bed every single night. My old LG Voyager had an "alarm only" setting (in addition to vibrate/silent /ringer) which makes more sense to me than "vibrate with alarm ring" or "silent with alarm ring". If my Voyager was set to vibrate and the alarm went off, it would just repeatedly vibrate. I am somewhat worried (always paranoid) that this is some kind of glitch and I'll have it set to vibrate overnight and one morning instead of ringing for my alarm it'll just vibrate over and over and I won't wake up. Being late to work is one of my biggest fears Is this the norm with other Dincs? I tried searching but there are so many alarm threads and questions and I am too tired to keep looking.