There aren't terribly many auto-flowering strains commercially available...so I'd have to agree that if you haven't started 12/12, then your plants are showing you their pre-flowers. If you want to keep on vegging, you certainly can, but just bear in mind that most varieties (especially sativas) can double, or triple in size by the end of flowering. If space is going to be an issue for you, you might want to start training those plants before flowering. Read up on LST, if you haven't already...that'll tell you everything you need to know.