If the light was flashing the alternator was not charging or the ELD in the fuse box may have been faulty. If the charging system is fine, battery holds charge, then there may be another draw.
With it being winter the cold temps can greatly affect the batteries ability to charge/maintain charge. Verify your electrical system is also in proper order. Verify the battery cables are clean, tight and not corroded. Verify the connections to the fuse box, starter and transmission main connections are clean and tight. Verify the body ground is clean and tight. Verify the main engine harness ground is clean, tight and not corroded. Verify the ground bonding jumper on the engine mount is installed correctly, clean, tight, and not corroded. Verify battery voltage in the morning before doing anything, 12.4-12.6 Volts.
Don't dismiss any potential draw without testing first.