Waller (undisclosed) sat out Thursday's practice, Adam Hill of the Las Vegas Review-Journal reports.
Waller, who had been previously been dealing with reported hamstring injury, returned to a limited session Wednesday, so it's possible that his absence from Thursday's practice is maintenance-related, rather than indicative of a setback. The tight end's status for Saturday's preseason game against the Dolphins is unclear, but if he's less than 100 percent at this stage, Waller could be held out for precautionary purposes.