Perhaps it's the large backlog of transactions waiting to get in blocks...
For anyone else wondering, Bitcoin Charts provides a view that will show the low priority transactions that have been announced to the nodes for processing by the miners. The low priority transactions generally have no fee, and/or have a low amount and/or use for inputs new coins that haven't "matured" by having a high number of confirmations).
Using the latest client (v0.3.21) instead of an ewallet service for sending small amounts will help (if the goal is to not encounter delays), as the client will now let you know when you are sending a low priority transaction.
Here's a related thread: