Does 20x TTE buffer REALLY expire? - polyacryamide gels; buffers (Nov/05/2007 )

I am going to attempt conformation-sensitive gel electrophoresis (CSGE) on a half-dozen samples. (This requires a polyacrylamide gel, and TTE (Tris/taurine/ETDA) buffer.) This isn't something the lab is going to do on a regular basis, so if possible, the PI would like me to use the reagents we already have. We have a bottle of 20xTTE buffer from 2002, and the bottle says that it has a three year shelf-life. My question is, how seriously should I take this expiration date? Does TTE degrade in some way? After all, both formamide and dextrose have expiration dates, and I know formamide de-deionizes and decomposes, whereas dextrose seems like it should be fine...
Thanks in advance,
KJM

Check if the cap has been tightly capped, CO2 may leak in and change the pH. Check if the solution turns yellow. NH2 may be oxidated over time to some degree, particularly when it is exposed to light. By large, I dont see a big problem.