Notebook with personal info lost

Grundlestiltskin

So long story short, I lost my notebook on Saturday (probably at a Boston T stop) and didn't realize until last night. In it was a copy of my lease, one of my checkbooks with just carbon copies left, and my girlfriend's checkbook. She's canceled the checks and it doesn't seem that there's been any suspicious activity, but I'm concerned.

My question is, is there anything that an unscrupulous person could do with our lease or our check routing numbers that I should be excessively worried about?