I have also seen this happen. Screen saver stays on but the paused playback goes away (I can tell because the sound from Live TV starts playing).
Another possible difference is if it's a true DVR recording, or a Cloud DVR recording. When paused, just look to see if there is a cloud icon next to the "DVR" text above the timebar.
A quick (20 minutes+) experiment would seem to indicate that the 10 minute pause limit seems to apply to Cloud DVR recordings only. But that brings up another question... How do I control which programs are recorded to which DVR (local or cloud)? A scan of my recent recordings shows that, of 3 recordings, 2 were recorded to local and 1 to the cloud. The reason I ask is that, if I record something that I want to save for a long time, I would want it in the cloud so that, if I had to swap out DVR boxes (in case of failure, upgrade, etc.), my recordings would be saved whereas short-term recordings, I could care less about since I watch them and delete them. I looked through Xfinity's Cloud DVR description and have, as yet, been able to find out what determines which recordings go where.
Unless you max out your cloud recording limit, anything recording locally is also available on the cloud.
Generally, a DVR will end up with a cloud recording if there is a signal or other communication issue during the recording, or if you are recording an IP channel. The DVR can only directly record QAM channels.
How do you know if a channel is IP? No obvious way. If you have HDMI audio mode set to Expert, I have noticed that it uses DD+ audio. But, you may need a separate A/V receiver to check. Also, they currently will be 1000+ channels that are NOT available in the sub-1000's. Most commonly, they are HD versions of otherwise SD-only, and a few newer channels.