It's hard to find the perfect time in fall to plant spring bulbs. They need a little time to grow some roots and nestle in, but not so much time that they start actively growing. Unfortunately, what the weather will be is anybody's guess, so it's not unheard of for bulbs to occasionally sprout in fall. It's also not something to be overly concerned about.
A handful of bulbs, like grape hyacinths (Muscari) and Dutch iris, regularly send up some growth in fall, but most do not, unless conditions are off. If the problem is that you planted too shallowly, take advantage of the warmer weather and gently lift the bulbs and plant them a few inches deeper. If you planted too early or if you're having an unusually warm fall, be patient, the weather will change.
Even if your bulbs send up some foliage in fall or during a winter thaw, they're probably just testing things out. They will stop growing on their own, once the temperatures drop. And the flower buds are already set, so you should still see plenty of flowers next spring. You only need to worry if the buds themselves poke above ground. Even then, you may lose a few flowers, but the bulbs will survive. Next year plan a little better and wait until the soil has cooled, especially for tulips. The first light frost is a good signal to get your bulbs in the ground.
Now, if you completely forgot to plant your bulbs... What to do with unplanted bulbs...
Photo: © Marie Iannotti