It happens!
It is caused by a doe being bred late.
If a doe is not bred when she is in estrus, she will come in estrus again 28 days later and then again 28 days after that.
Doe fawns usually do not come into estrus the first estrus cycle like older does but will come into estrus 28 days after that. Commonly called second rut.
Of coarse when bred late, fawns will be late.