It's the first flight of that Sherpa model, and they may not have planned to raise the orbit right away. As you pointed out though they can't wait too long.
The @SpaceflightInc Sherpa-LTC satellite, carrying Boeing's Varuna V-band demo payload, was launched almost a month ago. It has apparently not yet begun raising its orbit; orbital decay has already reduced its altitude by 15 km, with reentry within weeks if no orbit boost soon.
Five of the 51 Starlinks from the same launch (G4-20) also appear headed for premature immolation, but S-4644 appears to have been saved and is starting to raise its orbit.
Spaceflight spokesperson Jodi Sorenson told SpaceNews Oct. 4 that the company is still going through the post-launch commissioning process for the Sherpa tug. “As always with experimental, first-flight systems, the commissioning process is fluid,” she said, with orbit-raising maneuvers set to begin once commissioning is complete. She did not give an estimate of when the spacecraft commissioning will be completed.
Sherpa-LTC did make an orbit boost burn at around 1100 UTC Oct 7, from 280 x 292 km to 283 x 328 km, so looks like all is well aboard that spacecraft.
Revised orbit plot for that launch:
