Ok, so they didn't
come out and tell us what was going on in 6.06, but they sure told us all about Sam's missing soul in the 6.07 preview, didn't they? ;-)
So, here's the bunny:
After Sam shared Lucifer's cage for close to 2 years topside time, his brother and soulmate finally discovered the ritual to pull his soul back using their connection and Sam's remaining tether to his living body.
Finally free, Sam wants nothing more than for Dean to hold him and comfort him and make everything all better like he did when Sam was little.
Raw and vulnerable in ways he couldn't have imagined before, Sam wants nothing less than to be touched by anyone.