It's certainly not uncommon! I think a lot of us have realised that 'breakfast is the most important meal of the day' is something of a myth - mostly cooked up by the cereal industry to sell their products
When you're on 5:2 you start to be more aware of what your body needs as opposed to just what it wants. If you're not hungry in the morning you probably don't need to eat just yet!
I know I for one often don't eat until nearly midday after a fast, and actually if I eat earlier than that or if I eat too much then my tummy will tell me! I really love my cereal and have eaten it at breakfast time all my life but now I find more and more often I don't feel I need it, even if I might sometimes fancy it!
Likewise for lunch - I've often found myself eating lunch just because it's 'lunchtime' even though I wasn't hungry and didn't really know what to have as my body wasn't asking for anything in particular. But I felt like I had to eat because it's normal to do so. Well, I guess I probably didn't need my lunch all those years I forced it down myself, because I'd filled up at breakfast! Now I tend to miss breakfast and have a lunch instead (which sometimes is a bowl of cereal and some fruit, other times a salad, leftovers from yesterday, a sarnie... whatever my body seems to ask for).
So, don't worry - you're just more in tune with your body's needs

If however you should start feeling seriously unwell because of it then perhaps you need to look at changing your fasting dinner in order to influence the way you feel when you get up. I'm not sciency enough or foody enough to advise on that though!