To give an example of why you shouldn't bother with an amended return: Years ago (before tax software) I changed jobs and received stock from a stock savings plan (not 401(k)). I knew it counted as regular income, so I included it in the line for wages, salaries, etc. instead of the line it was supposed to go on. The IRS noticed I had income from the stock savings plan distribution and expected to see it on the return where it was supposed to go. Since they saw $0 on that line, they sent me a firm letter indicating I owed them a bunch of money for unclaimed income. I sent them a letter back (no email then, either) explaining my error and showing how my salary combined with the stock plan distribution accurately represented my income.
In a remarkably short time (couple weeks), I received a letter from the IRS indicating no further taxes were due and thanking me for my timely response.
So, if someone actually does notice what the IRS has received from your bank differs slightly from what you filed, you will likely just need to explain it without filing an amended return.
