737-800/900 opt/max altitude

I have a question for the 737-8/900 series. I'm climbing to the opt altitude and I let it sit there for a while to wait for the next opt altitude in my direction to show up. I've noticed that the OPT/MAX altitudes are within just a couple hundred feet of each other. Typically in the bigger jets you have an OPT of say 315 and a max of 346, mine right now is showing an OPT/MAX of FL311/FL333! What is going on with this feature? I was doing a long cross country with my takeoff 400 lbs under max gross and never made it above FL330 because when I tried to update the CRZ page to FL330 it went right to the DES page and I still had 2000 miles to go!!! Was there an update to the 800/900 that I did not see? Also, is there an install file that would allow me to install the 800/900 without having to do update installs after???MattProud owner of: PMDG 737-6/7/8/900, 747, MD11