i'd still say your battery is going bad.
the first sign of things going south is settings corruption. the lithium cells used in these older CCC's (as well as other battery backed RAM) have a peculiarity about them... they output their full voltage over the lifetime of the cell... but their current delivery capability drops.... then the voltage starts to tank.
It gets to the point where if you were to have one running an RTC RAM chip, you can actually see the clockticks as they consume current when they write to memory. write too many bits (a year, month,hour, and second) consecutively at the same time, the current draw of the writes sags the battery down enough to cause corruption elsewhere in the chip. (typically ever so slightly higher power consuming bits get killed first) the power consumed on standby is in the order of microamps... but by this point...the battery is only JUST capable of outputting only this much.
left alone i'd say in another couple months, your settings will be corrupted again... then a couple weeks after... as the battery is capable of outputting less and less current, it takes less and less bit writes to RAM to screw it up. you'll find your battery voltage has gone from 2.9 to under 2 volts. your current is gone and your voltage is now beginning to tank. before you know it, your setting no longer save and your battery voltage is 0.2v