Hey you are not the first to do that and you won't be the last! :kissy:
As JP says, sometimes it depends on the light and the angle... I have a vase which I swore was unmarked for months and months... then one day I found a very very feint Webbb Corbett mark. I'm sure the fairies snook in during the night and put it there because I'd searched for it loads of times and not seen it.
At least we know they are Stuart now. :thup: