mean that the interval for the next repetition was formerly set to 17, but got reduced down to 8?
Yes. Because of differences in the algorithms used for spacing repetitions in SuperMemo for Windows and in SuperMemo for Pocket PC, minor difficulties in planning future repetitions arise. This is most visible when you make many repetitions on Pocket PC before re-importing to a Windows collection. As a result, when SuperMemo for Windows is not sure about the exact repetition history and the optimum next interval, it errs on the safe side and uses a shorter interval before the next repetition. All such changes to intervals are reported to you.