Is it normal for your girlfriend sleepover her ex boyfriend's house (she say we are good friends now)?

My girlfriend is going to sleep her ex boyfriend's house..
So basically
Marie (my gf) went to james (first boyfriend... now she say we are good friends) house today
And she said she is going to sleep over and she went there 10 pm and still there
She literally texted me aus 1 am then no text
And it's 5.10 am there.
Basically he was the first boyfriend they broke up when they were 14-15 years old and then they stopped talking to each other and then again they started talking since last year and when they met last year she was single so had sex
She said they had 3 times
Once in james friends house
And this guy left for Australia and before he left they had sex
And now they together in Canada
And she is going to sleep in his house.
And also marie went there with her best friend Kate who is also a friend's of James. and kate returned back to her hostel at midnight.

I trust my girlfriend but I m feeling weird right now
Is this normal?
Is it normal for your girlfriend sleepover her ex boyfriend's house (she say we are good friends now)?
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