Suspicious was what it was, in Ulquiorra's view. There had been no such thing when he and Ienzo-san had run into the Weapon earlier, or at least, none that he had noticed, and Ulquiorra noticed things. The reiatsu of the Weapon permeated the environment, but it was, if he paid attention, coming from that direction.

The sensation was a little like trying to find the centre of a storm while standing in the midst of it.

The strange tendril was red, and waved, almost beckoning. Ulquiorra rested his hand on the hilt of his sword, leaving his other in his pocket. "An invitation," he said.

A taunt. A trap. How much sapience did the thing possess? In any case, it's reiatsu had not been discernible before its appearance last time. Now it's reiatsu blanketed the area, and something red, buried in the sands, waved for attention, calling them to investigate.

Unwary scientists and researchers might happen across it and be destroyed in an instant. After their battle, their escape, the Weapon couldn't be attempting to entice himself and Ienzo-san back to it; they would know better. Perhaps this was how it usually functioned. Perhaps Ienzo-san's chakra had alerted it to a threat, and woken it from centuries long slumber, and with their having fled it was reverting to its usual behaviour.