Bicycle Mechanics - BB question

So I went on slow casual 20 mile ride, mostly because it's raining and I hate riding fast in the rain.

But anyways I noticed when mashing or really pushing hard on the pedals I get kind of a knocking noise from the BB area. Only happens on the downstroke of the right pedal. So I took it to my LBS (still under 1yr warranty) and he said it sounds like the BB. So I told him I'd drop it off Monday.

So the question is, what could cause this? Something catastrophic to the frame/BB/crank? I didn't see any cracking around that area. Never been in a an accident. I'm guessing something wrong with the BB, but what in particular?

Thanks.

It may not be from your BB. It can be from many places - as this will show you, and help you diagnose and eradicate the problem:

http://www.sheldonbrown.com/creaks.html

BB typically refers to the cartridge (spindle & bearing assembly), not the shell/frame. Nothing catastrophic.

Thanks for the link. Based on sheldon's page I checked off everything I've already done.

Pedals: not loose, they actually tightened them when I got there just to make sure.

Crank Fixing bolt: wouldn't know, don't have the tool, never been removed

Stack bolts: have been properly torqued by me every time I remove them to clean the chainrings and the rest of the drivetrain

Bottom Bracket Cups/Retaining Rings Loose: don't have the tool, don't know, never been removed

Pedal Problem: spin fine, nothing wrong with them.

Bent Chainwheel: nope

Front Derailer Hitting Crank: I keep my drivetrain properly adjusted (plus this is more of a knock not a rubbing of the chain or metal on metal hitting)

Saddle Creaky: No, still happens when I mash out of the saddle

Handlebars/Stem Creaky:
Definitely not coming from the handlebars, I can actually feel the knocking when I pedal hard. It also happens when I'm in saddle light grip on handlebars and really pushing it. Also have ridden no-handed on the trainer to check as well.