When to worry about a change in a toddler's sleep?

[Stripylikeatiger]

My 2 year old usually sleeps 7.30-6ish with a 1/2 hour nap, the last few days he's slept until after 7, we have had to wake him to go to nursery. He's been a bit unsettled the last couple of nights I think he had a couple of bad dreams.

Should I be worried that he's more tired than usual?

They often sleep more after a growth spurt, could it be that?

I'm not sure if he's grown especially much, we also have a newborn do the toddler looks massive but it might just be in comparison to the baby.

He has been ill, he had a tummy big last week so maybe he's s bit tired from that.