First, I would look to the language of your lease. What does it say?

Section 1940.9 of the Civil Code spells out the requirements for this type of situation. It can be found at http://www.leginfo.ca.gov/cgi-bin/di...le=1940-1954.1

The fact that you haven't been billed for a long period of time is inappropriate. Nonetheless, you did agree to pay as part of your lease and I assume that as a responsible person, each month you have been setting an amount of money aside in anticipation of the day when payment would eventually be requested.

Assuming your lease is in compliance with the Civil Code, I would ask for copies of all the utility bills for the period in question so you can confirm the amount requested is correct and then cut a check for what you agreed to pay when you signed your lease. In the mean time, enjoy the interest you earned on the money you delayed having to pay, albeit small.