This happens to me for some time nearly every time the clocks go back or forward. It depends how different your basal rate is from hour to hour.. mine is pretty similar, so although it did make sense why I was going low if I didn't get out of bed at normal time (when I need more inslin seemingly just coz I'm moving around) it didn't make a huge difference.. Are you sure you didn't set up your pump before the clocks last changed? if so you could have been an hour out from the initial setup and haven't noticed so it probably isn't too much of a problem.