Health insurance question

I am very blessed to have great health insurance as I work for a school district. I am payroll and benefits manager but this is a personal concern.
6 weeks ago I took my husband to the ER with severe abdominal pain. He had a CT scan and later that afternoon had laparoscopic gall bladder surgery. He got 1 night in the hospital- semi-private room, regular floor not ICU.
We are self-insured with Aetna as administrator. Aetna was billed $65000 (!!!) by the hospital. That's just the hospital, not the surgeon or anesthesiologist. Those charges seemed reasonable. But $65000 for ONE NIGHT and an ER visit??? Of which my employer paid $27000! Since we're self-insured that's coming directly from my school and will certainly make our premium increase next year. What do they charge for a complicated illness with multiple days' stay??
I honestly think this is a mistake. Had an appendectomy 2 years ago (similar circumstances- ER visit, 1 night stay, same hospital - and I think Blue Cross (we had then) might have paid $5000.
Called Aetna and could not get a straight answer. Only "that's what they billed us, we paid our share and you owe $100." Like it wasn't my problem that my employer paid $27000.
Was this a mistake? Or is the list price for 1 night in the hospital really $65000??!