Fleas in Apartment After Professional Cleaning?

I lived in a townhouse for almost 3 years with my 2 dogs. These dogs are well taken care of, getting bathed regularly and groomed every 6-8 weeks. I have never had a flea problem with them and if I have, I've always treated them with a flea medicine and stopped the problem quickly. I never saw a flea in my residence that was crawling on me or on my furniture/carpet.

I recently moved out and part of my lease agreement was to have the carpets professionally cleaned. I took care of this as well as had the place professionally cleaned. Today, my landlord called me and told me the place was infested with fleas. She said that the new tenants claim that they found fleas in their bed, and since I've already been refunded my deposits, that I would be responsible for the bill for having the place treated.

My question is how can a place be infested when I "never" saw signs of fleas to begin with and my dogs have rarely ever had fleas on them? In fact, now that I think of it, I didn't ever have to treat them for fleas the entire time I lived there. My groomer never sees fleas on them either. Wouldn't I have noticed the fleas before leaving the place? Wouldn't having the carpets cleaned have taken care of any fleas/eggs?

I am at a loss for words and I honestly can't fathom how this could be my fault. The landlord told me that they normally hold the pet deposit for 30 days after vacating, but because my place had been taken care of and was so clean, she went ahead and sent me my deposit. I don't see how she can prove that the fleas came from me and my dogs. Wouldn't there be fleas on my dogs now and at my new place? I take my dogs with me to my parents' house very often. Wouldn't they have fleas at their house as well? I am just totally baffled and very much annoyed with this.

By Leah H.