The Guilt of Motherhood

Why do I feel so guilty?  I've just dropped Bode off for his morning of "school" today, and I feel like I've abandoned him. For four months now Bode has been going to day care one morning per week and by all accounts he has been thriving there.  Sure the first handful of weeks were tough, but he never cried and screamed (nor did I thankfully), and once he grew to trust that I would reliably be there to pick him up every single day, he began to relax and truly embrace his new, stimulating environment.  So just this week Bode began going to school two mornings per week instead of one.  He seemed perfectly content when I dropped him off this morning.  So why do I feel so guilty?