Overdrawn at the ... Bank

I logged into our First Bank account, because I wanted to check on a couple things (we are moving to a new checking account this week. When I got there, I saw that I was $45 overdrawn!!! So after a nice, long panic I found check #2111 (not my check). Ours are in the 600's. Someone else's check for $57 posted to our account.

Their electronic check reader (or human) read the 229 as 559 and it posted to our account.

We're saved? I hope so. Otherwise, we'd be facing over $100 in overdraft fees, 75% of which would be for purchases under $7.00