When blood is on your glass you should worry. Pushing is a common thing in retics - some people are open about it - others are just slightly set away from it because they don't want to talk about it or haven't experienced it.
Ambient can be perfect. Space perfect. Hides perfect, and it will still happen. There are two things to try - one has been mentioned, the other I don't believe has been. During pushing increase food. If pushing occurs on the cooler side, drop temperatures a little more. These guys enjoy the cooler end of the spectrum. 70 degrees is comfortable for some of them. Mine only go to heat after a big meal. Otherwise they stay around 72 degrees.
Other thing you can do is a little more proactive - get a two liter bottle and put some warm water in it and seal it tighter. Put the bottle in the enclosure. They like to push. So this is giving them something else to push around. Cage too small for that? use a 1 liter or 20 ounce bottle. This can offer them some preoccupation with the pushing and calms them down overtime.
Hope it helps.
Cheers