A notice of escaped assesment is a delayed re-assesment of the property taxes of your building. The first step is to determine if you or the lessor is responsible for the increased property taxes. Your lease will contain this information about which party is responsible. You may want to contact your lessor or the broker that helped you lease the property.
If your lease is a triple net lease with no expense stops, you may be responsible.
If your lease is a gross or modified gross lease, it may be the property owners responsibility.
Worst case, you may want to appeal to the county with the help of the property owner.
A re-assesment usually only occurs of the property was recently sold or significant improvements were made.
Feel free to let me know if you have any additional questions.