Don't know if this is normal but a couple of mine have those fine cracks in them. I would think that it was not a good sign but they have been there for 3 years now and have not gotten worse. I thought that it was a manufacturing flaw because I also have some just as old that have no cracks whatsoever. I'm gonna keep using them until they start to chip off.
I would have thought they would be a problem. I have seen chipped enamel, but not cracks. But it sounds like it is not a big deal at all. I guess that is why people love enamel cookware! Even when it is not perfect, it still works great.
I'm glad to see she is not the only one. If it's happening to others it's probably a normal process it goes through. As long as it doesn't cause any problems she can keep cooking with it. My sister-in-law bought her this one and I bought her a smaller pot to use for smaller foods since she really likes them on the gas oven. She's swears they cook better than other pots.
The official answer is not to use the item if the cracks/chips are on the inside. Chemicals in the enamel can leach into the food.
However, plenty of people continue to use the cookware with no adverse effects. I know we do! The biggest problem we had is taking care of the exposed iron. I make sure to always hand wash my enamel cast iron, whether chipped or not. After I dry it, I rub some shortening into the exposed area.
Yeah my mom has some 70+ year old french enamel over iron cook ware. I'm sure I have seen little cracks and chips but it still does a great job. If you are really concerned about the cracks check with the manufacturer as I'm sure they will let you know if its safe to use or not. I would suggest that there are no problems to keep using it as long as it isn't cooking differently.
Porcelain enamel pots are hard to maintain. There are a lot of things you cannot do with it like pre-heating it using a stove, washing it with a dishwasher and using it for deep fry. These are just of the many cautions one will have to keep in mind when using and maintaining a kind of this pot.