when my abs module failed it did it gradually.. abs light would come on.. then go back out the next day.. kept doing that until it was on more than it was off.. then it just stopped turning off til i replaced the module

some here think that working the abs will keep it from failing, so while it still functions, give it a good workout on some dirt or gravel roads (of course be safe about it!)

ive heard of the brake light coming on in cold weather due to the contact in the center console expanding/contracting or somethin like that.. maybe just condensation on the contacts from the cold weather because any time your windows fog up.. chances condensation happens on any metal surface inside the car until it warms up fully

check engine light i would guess is probably just caused by the gas sitting for 6 months in your lines.. if its out dont worry about it til it comes back