AITA for replying with an “ok” text?

We were invited to a buffet dinner with another couple and had to secure childcare so I asked my mom. When I called her at 4 pm we were on our way to her house (5 minutes away) but she informed me that she is at the casino. She doesn’t usually go anywhere and I knew she might have gone to the casino around lunch time but I figured she would be back by 3 or 4 like she said. My husband and I are first time parents with a 4 month old. I wasn’t even going to defend myself until my mom continued to tell me my texts weren’t clear. I genuinely think they were clear she just went out and didn’t think I was coming over.. idk. Should I have texted her back ok see you then or should she have texted me or called me to tell me she wouldn’t be home around 3-4 like she said she would be? Her and I both agreed could have done something I just feel like considering the circumstances the bigger burden to check was on her. Idk
Mom:Morning princess
Me:Hey mom we were invited to a buffet dinner with one of Eric's friends at 3:30-4 can you babysit?
Mom: Your dad has a cold but I feel ok. Glen,your sick dad , and i were going to pechanga around lunch. We should be back by 3
If you want to bring ej over I will watch him
Me: Maybe dad shouldn't go to pechanga lol.
Did you have a gnarly headache recently from the weather cuz I friggin did.
Mom: Your dad isn't going and yes he has had a gnarly headache