If they allow an over charge to go through, I would be angry because then they could, like you said, potentially charge over limit fees. I don't want over charges to go through!
Yeah. I used to get calls from customers all the time angry over this exact thing. Now, the timing had to be pretty bad for that to happen (because we only charged the fee if the account was over limit on the day the statement closed), but still...
If that happens, I'd just call Discover. If it was me you called, when I worked at the bank, I would have been able to waive the fee (as long as it hadn't been waived for you a bunch of times in the past).
However, official policy was: It is the
customer's responsibility to remain below their given credit limit, not the bank's to keep them on a leash.