Did Xolox crash or something, even earlier in the day. If so Xolox may not have been properly removed from memory. Even if the most recent instance did, it would only add and remove an extra Xolox. I have noticed that it seems to take Xolox a little time to get out of memory (no idea why), but if you have closed Xolox and it is not out of memory then you can always manually free that space.