When veileds first came into the pet trade 20+ years ago, many of us bred them around that age. Any time from 3.5 months on. There was a stupid rumor spread that if not bred as early as they were receptive, then they would die egg bound. So everyone bred them really early. Many of my offspring can be bred by that age if they were ever allowed- I chose not to because it is hard on the females and nowadays everyone knows better.
Depending on her size, it is totally possible that you have created a sibling pregnancy situation. Or she could just be really stressed from being around your male at 4 months of age still.
Either way, separate them and give her her own enclosure with a nest box, and visually isolate her from the male so they cannot see each other.
-Reminds me of the story of the time my father went to see a lady about a sick cat when he was still a young veterinarian. My father told her the cat wasn't sick it was pregnant. "Oh! That's IMPOSSIBLE! I never let her out of the house!". "Well- what about that tom cat over there?" " HE can't be the father! He's her brother!"
lol