Dealers do that ALL the time.
Pen stripes now days are basically just a vinyl sticker (as opposed to painted stripes), if that is what they are I would remove them even if they look good. Eventually they will either crack or peel, in which case you will probably want to remove them anyway. If you live in an area where its sunny all the time, there will be a slight color difference if its a year or so down the line (between the paint underneath the stripes and the normal paint). Most wont notice it, but you as the owner will. Its more or less like the rug over the carpet theory, even if the carpet appears to be in great shape the the stuff under the rug is brand new.
If you do decide to remove them, make sure they have NOT been cleared coated over. My guess is they have not.
But hey, the car looks hot

congrats on the purchase.