It's quite normal for a boy of his age to not be able to retract his foreskin yet. As he enters puberty, his penis will grow quicker than it does now and as more frequent erections occur, he will be able to fully retract it over a period of time as the skin needs time to separate from the head of the penis. (speaking from experience :)) However, 'phimosis' can occur in uncircumcised boys and men so it may be something to keep an eye on.
I dont think it sounds like a big concern at 11 year old but it may be something to ask your doctor about ,I doubt if the lack of circumision has anything to do with it, most Of Europe is uncircumsized and we all know the french do pretty well.It may be good to ask the Doc because of him being able to clean the area .good luck