I have also noticed lately that the blockchain.info wallet's "normal" fee calculations are very low recently.  I always make sure to double check the backlog and set my own fee manually so that this doesn't happen.  I almost missed one a while back, and if I wouldn't have caught it, I'd probably still have a transactions stuck for 3 weeks now.  It is always best to set a custom fee (on wallets that allow it) to avoid "stuck" transactions.