I have also heard about the $10,000 dollar "trigger", and I can assure you from experience, it doesn't even have to be that much.
I had $5000 that I was going to purchase a used car with, but while I was looking for a suitable vehicle, I was using that cash to obtain new bills from the bank. The manager at one bank decided that I looked criminal and made me fill out a declaration form, giving S.I.N. number, drivers license and numerous other bits of personal information. I asked why, since I had recycled this cash about 6 times before this happened. She gave me a song and dance about how it is "standard proceedure" when dealing with such a large amount of cash (only $5000 remember).
I guess she just got nervous that I was ordering new bills in quantity, and paying with cash. I didn't care. I was polite, thought of a number of nasty names for her, got my notes, and ended up with four K/T BEF $10's. I get ill when I think of the other 496 I returned to the bank.