Yes, it's unfortunately a known issue with some Nook ST's.
Read this thread and the very helpful post from RAH: HERE
Here's a summary of RAH's technique:
"1) charging it to 100%
2) let it sleep over night/ Next morning it might be around 88% (i.e. terrible battery drain)
3) connect it to your computer via USB cable and let it charge again up to 100% (i.e. "top it off")
This has ALWAYS fixed the drain problem for me. After doing this, it only loses about 2 or 3% per day (sleeping or using, no WiFi).
RAH's top-off technique works 100% of the time for me!