Just curious, what was the size of your "small carry on" and what was the size of your "personal item"

If you only had two items and you already put the smaller of the two under your seat, I don't see why you wouldn't be allowed to put the other overhead.
However I guess it depends how small each are. If one if one is a purse and the other is a laptop bag, I'd argue both could easily fit.
If you had a duffle bag and a backpack, I would think it is unreasonable.