Was the retic under a UV light of any kind (viewing purposes, maybe)? Baytril belongs to a class of antibiotics that can cause sensitivity to sunlight (obviously not an issue for snakes who live in their hides/don't have a UV light on them)!

And yes, you should make every attempt to keep to the dosing schedule...the reason for this is that it's apparently been established that a dose of Baytril every 24 hours will keep the antibiotic in its "theraputic range" within the body...ie. enough to take care of the bacteria without causing a toxicity to the snake (too much antibiotic) or too little to cause the bacteria to develop a resistance to the bacteria. Taking the "dose every 24 hours" schedule, if you give the initial dose at 8 p.m. then give the next dose at 3 p.m. the next day the level of antibiotics in the body may rise to toxic levels because the body hasn't had a chance to eliminate enough of the first dose just yet. Likewise, if you gave your initial dose at 8 p.m. and then give the next one at 11 p.m. the next night, the antibiotic level in the body may have dropped to below its theraputic range within the body during that 3 hour lag (ie. there isn't enough antibiotics in the body to fight the infection) allowing bacteria to develop a resistance in its next generation.

Now whether 1 hour either way will make a significant difference, I can't say as I'm not familiar with the snake's metabolism...but it's certainly a risk you take by giving an antibiotic too soon/a little late. Hope this helps!