Being a dog groomer myself, I am very familiar with flea season. If you feed the birds, watch for squirrels and wild rabbits feeding on the birdseed. Keep your grass cut short especially in that area because fleas don't like the sunlight. Dogs, cats, and people can carryfleas into the house, especially the hungry baby ones that just hatched and are more difficult to see.
In the house, walk around with white socks on because you will be able to see them if they jump on you. If you found one, expect to find others so don't just treat the animal. You will more than likely have to treat the areas that your pet(s) go into. Vacuum the entire area very well especially along the baseboards and any crevices. Best to be safe by throwing the vacuum bag into another bag that can be tied up for disposal. Fleas can live through anything even vacuuming. I usually try to catch them between my finger nails and split them in half (they still think they are alive even after that!!). You would have to find something bunny-safe to spray in the areas after vacuuming in case there are still baby fleas waiting to hatch. If you can't find a safe spray you might end up repeating sock, flea comb, and vacuum procedure until you think they are gone. I don't recollect the time span for new hatch-lings, but I would say five to seven days.
As always, use the safest product for flea management if you need to treat your bunny directly. If you do a treatment, watch for fleas aroung moisture areas or "safe" places for them to hide to get away from the treatment (eyes, ears, nose, mouth, butt-end). (I had groomed a dog once that was wearing a flea collar. The dog was completelyinfested with fleas except around the neck where the collar was)
I only found one flea on Miss Maggie some years back, but I was able to catch it before it ever made its way into the house (whew!). Ever since then, I watch for squirrels in the spring and fall of the year, make sure grass in short, leaves are picked up, and I do a quick flea-check by stroking the hair against the grain to expose the skin and any critters hitching a ride.
I hope your situation isn't serious and you caught it in time. Watch your baby(ies) for tapeworms also. Bunnies will get tapeworms from eating up the fleas that are causing them distress. So keep an eye out for anything that looks like a grain of rice or a small worm-like thing in or aroundthe droppings or the butt of the bunny. Fleas are nasty things and I wouldn't wish them on anyone.
myheart