Accidental Baytril Overdose

Hi y'all! I have 3 rats and a couple are showing symptoms of URIs. After finding some really helpful guidance here, I bought enrofloxacin (10%) to treat them. I weighed them and used a dosage chart to find the right dose, and then absolutely mis-measured when I gave them their first dose this morning. They were supposed to get 0.04ml and I gave 0.4ml. Thankfully, neither rat took the full amount because they hated it (for good reason, I'm sure it tasted foul). From what I'm reading, even though this was a pretty significant overdose, a single dose that big shouldn't hurt them in the long run. I'm posting here I guess for reassurance / if anyone has a similar experience. Currently my plan is to keep an eye on them both and take them to the vet if they start exhibiting any scary symptoms, and I will not be giving them a second dose tonight.

Couple of questions:

Is there anything else I should watch for?

When should I give them another (correct, this time) dose?