We had a ton that our visitors had carried into various corners of the basement. Also, be sure to store your dog food in an airtight container as well. Rodents can smell through the paper and will eat through the bag to get to the food. You don't mention if yours is a new home or not but here is some depressing news. Once you have had a rodent problem, you will probably continue to have some problem.
Rodents can smell the old urine from other rodents.
Thus, in future years, rodents may continue to try to enter your home at this time of year while leaving your neighbors' homes alone. Try is the key word here. If you continue to be vigilant, you should not have a re-occuring problem. As I mentioned, we trapped over 2 dozen mice ourselves last summer. We also had several nests in the insulation of our unfinished basement.