The fact that he already knows there's a chance of awkwardness, says his approach was short and he subconsciously doesn't feel confident he did enough to actually take her out. Many girls give out numbers without the intent of ever taking up the offer because saying no is more awkward than just giving the number. Especially in college. Hot girls in college get asked their number constantly, the ones that get somewhere are the ones that build more value than a simple approach and ask for number.
That's just my experience in a college atmosphere.