If you see the panic button in front of you, I wouldn't press it yet. According to the Baltimore Sun's Aaron Wilson, someone might have had an issue when reporting to camp on Friday:
Browns OG Eric Steinbach also placed on non-football injury/active list.less than a minute ago via web 
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Aaron Wilson
RavensInsider
If Eric Steinbach is indeed on this list, by rule, he still counts towards the team's 90-man roster. This probably means he failed a conditioning test, either from not being in shape or from having some lingering offseason injury. It's not like teams don't put their players on this list. In 2009, the Browns placed receiver Braylon Edwards on the list after he failed his physical.
This year, the Bengals and the Ravens placed linebackers Keith Rivers and Terrell Suggs on the list, respectively, for a wrist and hamstring injuries. As soon as Steinbach is medically cleared to play again, he can be taken off the list. The benefit of placing a player on this list is that when the regular season starts, if a problem still exists, it gives the team options to place them on another list until Week 6 or so.
Lastly, according to Evan Moore on Twitter, he officially signed his tender to be a part of the club this season.