Am I too old to change jobs?

I have an opportunity to maybe interview for another firm that is closer to the house.  I've been at the same place for 20 plus years and I'm no spring chicken as they say.  I'm maxed out on vacation here and I use most of it.  I've gotten comfortable in my work and maybe that is the problem.  I've been feeling for quite some time that God is slowly pushing me to get out of my comfort zone and try something new.  I always thought it was another line of work, but maybe it's just to go somewhere else. 

I"m a programmer, but a specialized one and I've had little opportunity to change that where I currently work.  I've wanted to broaden my skill set for quite sometime.  I had really in my mind given up on it.  The future looked like it was the same old same old and I had little power to change that until a couple of years ago and even then it was you are going to do the same things, but for a central department that is located somewhere else and you will be required to interview for your job again when we get to your division.  Sounds like fun huh?  I've been praying off and on since then for God to show me my next step. 

This week I was asked for my resume for another business that is close to my home.  I'm a little out of my comfort zone even doing a phone interview, but I feel God pushing me to at least take that first step.  I'm going to obey, but I still have the nagging question of how old is too old to switch companies???