[Landlord- CA] Tenant did not pay on the 1st

So this new tenant has been paying on the 1st (on time) for the past 5 months. Unfortunately this month, she did not send her rent. I know she has a 3 day grace period but is this maybe a slight red flag or am I thinking too much into it? It’s just, im not used to her paying later and she has great credit so im not sure this is a 1 off thing or if this is something i need to get used to going forward. She had a roommate but it looks like she moved out so not sure if she is having a hard time maybe but I would think she would reach out or something? She alone makes decent and can cover rent but she also works for the county so not sure if they are affected during this federal shutdown? 😭