Adopted dog 3 days ago, now other recently adopted dog won't come inside.

3 weeks ago we adopted Major (boy), a happy GSD cross who’s been moved around a lot in his short 18months of life. A few days he in normalised and has been a happy, comfortable dog.

Then, 3 days ago we took in another dog in distress, also a GSD cross. Maddy (girl) is 6 years old and has clearly been a street dog. She was rattled the first night, but is now quite comfortable as well.

Their meeting was a little aggressive at first (from her side, he just wanted to play) but once we brought them home, they coexisted in peace, mostly, and kept to themselves.

Over the past couple of days, when Maddy is lying near me, she will softly growl at Major when he comes in. The problem is that now he is hesitant to come inside the house and I’m worried that taking on Maddy has had a negative impact on Major. When I walk them together, feed them, etc, they are totally fine, It’s just an issue when she is in the house and he wants to come in (they are both inside dogs).

Has anyone had similar issues or have any advice to offer? Am I being paranoid? I just desperately want two dogs who have had tough lives to enjoy our home and feel safe.

Thanks
Ash